#![allow(dead_code)]
#![allow(unused)]

#[macro_use]
extern crate lazy_static;

extern crate chrono;
extern crate num_traits;
extern crate rust_decimal;

#[cfg(test)]
extern crate pyo3;

use chrono::DateTime;
use chrono::Datelike;
use chrono::FixedOffset;
use chrono::Local;
use chrono::NaiveDate;
use chrono::NaiveDateTime;
use chrono::NaiveTime;
use chrono::Timelike;
use chrono::Utc;
use num_traits::cast::ToPrimitive;
use rust_decimal::Decimal;
use rust_decimal::Error as DecimalError;
use std::collections::HashMap;
use std::num::ParseIntError;
use std::str::FromStr;
use std::vec::Vec;

#[cfg(test)]
mod tests;

lazy_static! {
    static ref ZERO: Decimal = Decimal::new(0, 0);
    static ref ONE: Decimal = Decimal::new(1, 0);
    static ref TWENTY_FOUR: Decimal = Decimal::new(24, 0);
    static ref SIXTY: Decimal = Decimal::new(60, 0);
}

#[derive(Debug, PartialEq)]
pub enum ParseInternalError {
    // Errors that indicate internal bugs
    YMDEarlyResolve,
    YMDValueUnset(Vec<YMDLabel>),
    ParseIndexError,
    InvalidDecimal,
    InvalidInteger,

    // Python-style errors
    ValueError(String),
}

impl From<DecimalError> for ParseInternalError {
    fn from(err: DecimalError) -> Self {
        ParseInternalError::InvalidDecimal
    }
}

impl From<ParseIntError> for ParseInternalError {
    fn from(err: ParseIntError) -> Self {
        ParseInternalError::InvalidInteger
    }
}

#[derive(Debug)]
pub enum ParseError {
    InternalError(ParseInternalError),
    InvalidMonth,
    UnrecognizedToken(String),
    InvalidParseResult(ParsingResult),
    AmPmWithoutHour,
    InvalidHour,
    TimezoneUnsupported,
}

impl From<ParseInternalError> for ParseError {
    fn from(err: ParseInternalError) -> Self {
        ParseError::InternalError(err)
    }
}

type ParseResult<I> = Result<I, ParseError>;
type ParseIResult<I> = Result<I, ParseInternalError>;

pub struct Tokenizer {
    token_stack: Vec<String>,
    parse_string: String,
}

#[derive(Debug)]
enum ParseState {
    Empty,
    Alpha,
    AlphaDecimal,
    Numeric,
    NumericDecimal,
}

impl Tokenizer {
    fn new(parse_string: String) -> Self {
        Tokenizer {
            token_stack: Vec::new(),
            parse_string: parse_string.chars().rev().collect(),
        }
    }
}

impl Iterator for Tokenizer {
    type Item = String;

    fn next(&mut self) -> Option<Self::Item> {
        if !self.token_stack.is_empty() {
            return Some(self.token_stack.pop().unwrap());
        };
        if self.parse_string.is_empty() {
            return None;
        };

        let mut char_stack: Vec<char> = Vec::new();
        let mut seen_letters = false;
        let mut state = ParseState::Empty;

        while let Some(next) = self.parse_string.pop() {
            match state {
                ParseState::Empty => {
                    if next.is_numeric() {
                        state = ParseState::Numeric;
                        char_stack.push(next);
                    } else if next.is_alphabetic() {
                        state = ParseState::Alpha;
                        seen_letters = true;
                        char_stack.push(next);
                    } else if next.is_whitespace() {
                        char_stack.push(' ');
                        break;
                    } else {
                        char_stack.push(next);
                        break;
                    }
                }
                ParseState::Alpha => {
                    if next.is_alphabetic() {
                        char_stack.push(next);
                    } else if next == '.' {
                        state = ParseState::AlphaDecimal;
                        char_stack.push(next);
                    } else {
                        // We don't recognize the character, so push it back
                        // to be handled later.
                        self.parse_string.push(next);
                        break;
                    }
                }
                ParseState::AlphaDecimal => {
                    if next == '.' || next.is_alphabetic() {
                        char_stack.push(next);
                    } else if next.is_numeric() && char_stack.last().unwrap().clone() == '.' {
                        char_stack.push(next);
                        state = ParseState::NumericDecimal;
                    } else {
                        self.parse_string.push(next);
                        break;
                    }
                }
                ParseState::Numeric => {
                    if next.is_numeric() {
                        char_stack.push(next);
                    } else if next == '.' || (next == ',' && char_stack.len() >= 2) {
                        char_stack.push(next);
                        state = ParseState::NumericDecimal;
                    } else {
                        // We don't recognize the character, so push it back
                        // to be handled later
                        self.parse_string.push(next);
                        break;
                    }
                }
                ParseState::NumericDecimal => {
                    if next == '.' || next.is_numeric() {
                        char_stack.push(next);
                    } else if next.is_alphabetic() && char_stack.last().unwrap().clone() == '.' {
                        char_stack.push(next);
                        state = ParseState::AlphaDecimal;
                    } else {
                        self.parse_string.push(next);
                        break;
                    }
                }
            }
        }

        // I like Python's version of this much better:
        // needs_split = seen_letters or char_stack.count('.') > 1 or char_stack[-1] in '.,'
        let dot_count = char_stack.iter().fold(0, |count, character| {
            count + (if character == &'.' { 1 } else { 0 })
        });
        let needs_split = seen_letters || dot_count > 1 || char_stack.last().unwrap() == &'.'
            || char_stack.last().unwrap() == &',';
        let final_string: String = char_stack.into_iter().collect();

        let mut tokens = match state {
            ParseState::Empty => vec![final_string],
            ParseState::Alpha => vec![final_string],
            ParseState::Numeric => vec![final_string],
            ParseState::AlphaDecimal => {
                if needs_split {
                    decimal_split(&final_string, false)
                } else {
                    vec![final_string]
                }
            }
            ParseState::NumericDecimal => {
                if needs_split {
                    decimal_split(&final_string, dot_count == 0)
                } else {
                    vec![final_string]
                }
            }
        }.into_iter()
            .rev()
            .collect();

        self.token_stack.append(&mut tokens);
        // UNWRAP: Previous match guaranteed that at least one token was added
        Some(self.token_stack.pop().unwrap())
    }
}

fn decimal_split(characters: &str, cast_period: bool) -> Vec<String> {
    let mut token_stack: Vec<String> = Vec::new();
    let mut char_stack: Vec<char> = Vec::new();
    let mut state = ParseState::Empty;

    for c in characters.chars() {
        match state {
            ParseState::Empty => {
                if c.is_alphabetic() {
                    char_stack.push(c);
                    state = ParseState::Alpha;
                } else if c.is_numeric() {
                    char_stack.push(c);
                    state = ParseState::Numeric;
                } else {
                    let character = if cast_period { '.' } else { c };
                    token_stack.push(character.to_string());
                }
            }
            ParseState::Alpha => {
                if c.is_alphabetic() {
                    char_stack.push(c);
                } else {
                    token_stack.push(char_stack.iter().collect());
                    char_stack.clear();
                    let character = if cast_period { '.' } else { c };
                    token_stack.push(character.to_string());
                    state = ParseState::Empty;
                }
            }
            ParseState::Numeric => {
                if c.is_numeric() {
                    char_stack.push(c);
                } else {
                    token_stack.push(char_stack.iter().collect());
                    char_stack.clear();
                    let character = if cast_period { '.' } else { c };
                    token_stack.push(character.to_string());
                    state = ParseState::Empty;
                }
            }
            _ => panic!("Invalid parse state during decimal_split()"),
        }
    }

    match state {
        ParseState::Alpha => token_stack.push(char_stack.iter().collect()),
        ParseState::Numeric => token_stack.push(char_stack.iter().collect()),
        ParseState::Empty => (),
        _ => panic!("Invalid parse state during decimal_split()"),
    }

    token_stack
}

pub fn tokenize(parse_string: &str) -> Vec<String> {
    let tokenizer = Tokenizer::new(parse_string.to_owned());
    tokenizer.collect()
}

fn parse_info(vec: Vec<Vec<&str>>) -> HashMap<String, usize> {
    let mut m = HashMap::new();

    if vec.len() == 1 {
        for (i, val) in vec.get(0).unwrap().into_iter().enumerate() {
            m.insert(val.to_lowercase(), i);
        }
    } else {
        for (i, val_vec) in vec.into_iter().enumerate() {
            for val in val_vec.into_iter() {
                m.insert(val.to_lowercase(), i);
            }
        }
    }

    m
}

#[derive(Debug, PartialEq)]
struct ParserInfo {
    jump: HashMap<String, usize>,
    weekday: HashMap<String, usize>,
    months: HashMap<String, usize>,
    hms: HashMap<String, usize>,
    ampm: HashMap<String, usize>,
    utczone: HashMap<String, usize>,
    pertain: HashMap<String, usize>,
    tzoffset: HashMap<String, usize>,
    dayfirst: bool,
    yearfirst: bool,
    year: i32,
    century: i32,
}

impl Default for ParserInfo {
    fn default() -> Self {
        let year = Local::now().year();
        let century = year / 100 * 100;

        ParserInfo {
            jump: parse_info(vec![
                vec![
                    " ", ".", ",", ";", "-", "/", "'", "at", "on", "and", "ad", "m", "t", "of",
                    "st", "nd", "rd", "th",
                ],
            ]),
            weekday: parse_info(vec![
                vec!["Mon", "Monday"],
                vec!["Tue", "Tues", "Tuesday"],
                vec!["Wed", "Wednesday"],
                vec!["Thu", "Thurs", "Thursday"],
                vec!["Fri", "Friday"],
                vec!["Sat", "Saturday"],
                vec!["Sun", "Sunday"],
            ]),
            months: parse_info(vec![
                vec!["Jan", "January"],
                vec!["Feb", "February"],
                vec!["Mar", "March"],
                vec!["Apr", "April"],
                vec!["May"],
                vec!["Jun", "June"],
                vec!["Jul", "July"],
                vec!["Aug", "August"],
                vec!["Sep", "Sept", "September"],
                vec!["Oct", "October"],
                vec!["Nov", "November"],
                vec!["Dec", "December"],
            ]),
            hms: parse_info(vec![
                vec!["h", "hour", "hours"],
                vec!["m", "minute", "minutes"],
                vec!["s", "second", "seconds"],
            ]),
            ampm: parse_info(vec![vec!["am", "a"], vec!["pm", "p"]]),
            utczone: parse_info(vec![vec!["UTC", "GMT", "Z"]]),
            pertain: parse_info(vec![vec!["of"]]),
            tzoffset: parse_info(vec![vec![]]),
            dayfirst: false,
            yearfirst: false,
            year: year,
            century: century,
        }
    }
}

impl ParserInfo {
    fn get_jump(&self, name: &str) -> bool {
        self.jump.contains_key(&name.to_lowercase())
    }

    fn get_weekday(&self, name: &str) -> Option<usize> {
        self.weekday.get(&name.to_lowercase()).cloned() // TODO: Why do I have to clone a primitive?
    }

    fn get_month(&self, name: &str) -> Option<usize> {
        self.months.get(&name.to_lowercase()).map(|u| u + 1)
    }

    fn get_hms(&self, name: &str) -> Option<usize> {
        self.hms.get(&name.to_lowercase()).cloned()
    }

    fn get_ampm(&self, name: &str) -> Option<bool> {
        if let Some(v) = self.ampm.get(&name.to_lowercase()) {
            Some(v.to_owned() == 1)
        } else {
            None
        }
    }

    fn get_pertain(&self, name: &str) -> bool {
        self.pertain.contains_key(&name.to_lowercase())
    }

    fn get_utczone(&self, name: &str) -> bool {
        self.utczone.contains_key(&name.to_lowercase())
    }

    fn get_tzoffset(&self, name: &str) -> Option<usize> {
        if self.utczone.contains_key(&name.to_lowercase()) {
            Some(0)
        } else {
            self.tzoffset.get(&name.to_lowercase()).cloned()
        }
    }

    fn convertyear(&self, year: i32, century_specified: bool) -> i32 {
        let mut year = year;

        if year < 100 && !century_specified {
            year += self.century;
            if year >= self.year + 50 {
                year -= 100;
            } else if year < self.year - 50 {
                year += 100
            }
        }

        year
    }

    // TODO: Should this be moved elsewhere?
    fn validate(&self, res: &mut ParsingResult) -> bool {
        if let Some(y) = res.year {
            res.year = Some(self.convertyear(y, res.century_specified))
        };

        if res.tzoffset == Some(0) && res.tzname.is_none() || res.tzname == Some("Z".to_owned()) {
            res.tzname = Some("UTC".to_owned());
            res.tzoffset = Some(0);
        } else if res.tzoffset != Some(0) && res.tzname.is_some()
            && self.get_utczone(res.tzname.as_ref().unwrap())
        {
            res.tzoffset = Some(0);
        }

        true
    }
}

fn days_in_month(year: i32, month: i32) -> Result<i32, ParseError> {
    let leap_year = match year % 4 {
        0 => year % 400 == 0,
        _ => false,
    };

    match month {
        2 => if leap_year {
            Ok(29)
        } else {
            Ok(28)
        },
        1 | 3 | 5 | 7 | 8 | 10 | 12 => Ok(31),
        4 | 6 | 9 | 11 => Ok(30),
        _ => Err(ParseError::InvalidMonth),
    }
}

#[derive(Debug, Hash, PartialEq, Eq)]
pub enum YMDLabel {
    Year,
    Month,
    Day,
}

#[derive(Debug, Default)]
struct YMD {
    _ymd: Vec<i32>, // TODO: This seems like a super weird way to store things
    century_specified: bool,
    dstridx: Option<usize>,
    mstridx: Option<usize>,
    ystridx: Option<usize>,
}

impl YMD {
    fn len(&self) -> usize {
        self._ymd.len()
    }

    fn could_be_day(&self, val: i32) -> bool {
        if self.dstridx.is_some() {
            false
        } else if self.mstridx.is_none() {
            (1 <= val) && (val <= 31)
        } else if self.ystridx.is_none() {
            // UNWRAP: mstridx guaranteed to have a value
            // TODO: Justify unwrap for self._ymd
            let month = self._ymd[self.mstridx.unwrap()];
            1 <= val && (val <= days_in_month(2000, month).unwrap())
        } else {
            let month = self._ymd[self.mstridx.unwrap()];
            let year = self._ymd[self.ystridx.unwrap()];
            1 <= val && (val <= days_in_month(year, month).unwrap())
        }
    }

    fn append(&mut self, val: i32, label: Option<YMDLabel>) -> ParseIResult<()> {
        let mut label = label;

        // TODO: Duck typing with val being an array type?
        if val > 100 {
            self.century_specified = true;
            match label {
                None => label = Some(YMDLabel::Year),
                Some(YMDLabel::Year) => (),
                _ => {
                    return Err(ParseInternalError::ValueError(format!(
                        "Invalid label: {:?}",
                        label
                    )))
                }
            }
        }

        self._ymd.push(val);

        match label {
            Some(YMDLabel::Month) => {
                if self.mstridx.is_some() {
                    Err(ParseInternalError::ValueError(
                        "Month already set.".to_owned(),
                    ))
                } else {
                    self.mstridx = Some(self._ymd.len() - 1);
                    Ok(())
                }
            }
            Some(YMDLabel::Day) => {
                if self.dstridx.is_some() {
                    Err(ParseInternalError::ValueError(
                        "Day already set.".to_owned(),
                    ))
                } else {
                    self.dstridx = Some(self._ymd.len() - 1);
                    Ok(())
                }
            }
            Some(YMDLabel::Year) => {
                if self.ystridx.is_some() {
                    Err(ParseInternalError::ValueError(
                        "Year already set.".to_owned(),
                    ))
                } else {
                    self.ystridx = Some(self._ymd.len() - 1);
                    Ok(())
                }
            }
            None => Err(ParseInternalError::ValueError("Missing label.".to_owned())),
        }
    }

    fn resolve_from_stridxs(
        &mut self,
        strids: &mut HashMap<YMDLabel, usize>,
    ) -> ParseIResult<(i32, i32, i32)> {
        if strids.len() == 2 {
            let missing_key = if !strids.contains_key(&YMDLabel::Year) {
                YMDLabel::Year
            } else if !strids.contains_key(&YMDLabel::Month) {
                YMDLabel::Month
            } else {
                YMDLabel::Day
            };

            let strids_vals: Vec<usize> = strids.values().map(|u| u.clone()).collect();
            let missing_val = if !strids_vals.contains(&0) {
                0
            } else if !strids_vals.contains(&1) {
                1
            } else {
                2
            };

            strids.insert(missing_key, missing_val);
        }

        if self._ymd.len() != 3 || strids.len() != 3 {
            return Err(ParseInternalError::YMDEarlyResolve);
        }

        // TODO: Why do I have to clone &usize? Isn't it Copy?
        Ok((
            self._ymd[strids.get(&YMDLabel::Year).unwrap().clone()],
            self._ymd[strids.get(&YMDLabel::Month).unwrap().clone()],
            self._ymd[strids.get(&YMDLabel::Day).unwrap().clone()],
        ))
    }

    fn resolve_ymd(&mut self, yearfirst: bool, dayfirst: bool) -> ParseIResult<(i32, i32, i32)> {
        let len_ymd = self._ymd.len();
        let mut year: Option<i32> = None;
        let mut month: Option<i32> = None;
        let mut day: Option<i32> = None;
        let mut other: Option<i32> = None;

        let mut strids: HashMap<YMDLabel, usize> = HashMap::new();
        self.ystridx
            .map(|u| strids.insert(YMDLabel::Year, u.clone()));
        self.mstridx
            .map(|u| strids.insert(YMDLabel::Month, u.clone()));
        self.dstridx
            .map(|u| strids.insert(YMDLabel::Day, u.clone()));

        // TODO: More Rustiomatic way of doing this?
        if self._ymd.len() == strids.len() && strids.len() > 0 || (self._ymd.len() == 3 && strids.len() == 2) {
            return self.resolve_from_stridxs(&mut strids);
        };

        // TODO: More Rustiomatic? Too many blocks for my liking
        // Also having the array unpacking syntax is nice
        if len_ymd > 3 {
            return Err(ParseInternalError::ValueError(
                "More than three YMD values".to_owned(),
            ));
        } else if len_ymd == 1 || (self.mstridx.is_some() && len_ymd == 2) {
            if self.mstridx.is_some() {
                month = Some(self._ymd[self.mstridx.unwrap()]);
                other = if len_ymd == 1 { Some(self._ymd[0]) } else { Some(self._ymd[1 - self.mstridx.unwrap()]) };
            } else {
                other = Some(self._ymd[0]);
            }

            if len_ymd > 1 || self.mstridx.is_some() {
                if other.unwrap_or(0) > 31 {
                    year = other;
                } else {
                    day = other;
                }
            }
        } else if len_ymd == 2 {
            if self._ymd[0] > 31 {
                year = Some(self._ymd[0]);
                month = Some(self._ymd[1]);
            } else if self._ymd[1] > 31 {
                month = Some(self._ymd[0]);
                year = Some(self._ymd[1]);
            } else if dayfirst && self._ymd[1] <= 12 {
                day = Some(self._ymd[0]);
                month = Some(self._ymd[1]);
            } else {
                month = Some(self._ymd[0]);
                day = Some(self._ymd[1]);
            }
        } else if len_ymd == 3 {
            if self.mstridx == Some(0) {
                if self._ymd[1] > 31 {
                    month = Some(self._ymd[0]);
                    year = Some(self._ymd[1]);
                    day = Some(self._ymd[2]);
                } else {
                    month = Some(self._ymd[0]);
                    day = Some(self._ymd[1]);
                    year = Some(self._ymd[2]);
                }
            } else if self.mstridx == Some(1) {
                if self._ymd[0] > 31 || (yearfirst && self._ymd[2] <= 31) {
                    year = Some(self._ymd[0]);
                    month = Some(self._ymd[1]);
                    day = Some(self._ymd[2]);
                } else {
                    day = Some(self._ymd[0]);
                    month = Some(self._ymd[1]);
                    year = Some(self._ymd[2]);
                }
            } else if self.mstridx == Some(2) {
                // It was in the original docs, so: WTF!?
                if self._ymd[1] > 31 {
                    day = Some(self._ymd[0]);
                    year = Some(self._ymd[1]);
                    month = Some(self._ymd[2]);
                } else {
                    year = Some(self._ymd[0]);
                    day = Some(self._ymd[1]);
                    month = Some(self._ymd[2]);
                }
            } else {
                if self._ymd[0] > 31 || self.ystridx.unwrap() == 0
                    || (yearfirst && self._ymd[1] <= 12 && self._ymd[2] <= 31)
                {
                    if dayfirst && self._ymd[2] <= 12 {
                        year = Some(self._ymd[0]);
                        day = Some(self._ymd[1]);
                        month = Some(self._ymd[2]);
                    } else {
                        year = Some(self._ymd[0]);
                        month = Some(self._ymd[1]);
                        day = Some(self._ymd[2]);
                    }
                } else if self._ymd[0] > 12 || (dayfirst && self._ymd[1] <= 12) {
                    day = Some(self._ymd[0]);
                    month = Some(self._ymd[1]);
                    year = Some(self._ymd[2]);
                } else {
                    month = Some(self._ymd[0]);
                    day = Some(self._ymd[1]);
                    year = Some(self._ymd[2]);
                }
            }
        }

        // TODO: Remove the error handling here
        // We should be able to justify the UNWRAP, but I haven't
        // convinced myself of that quite yet.
        if !year.and(month).and(day).is_some() {
            let mut ymd_unset = Vec::new();
            if year.is_none() { ymd_unset.push(YMDLabel::Year) }
            else if month.is_none() { ymd_unset.push(YMDLabel::Month) }
            else { ymd_unset.push(YMDLabel::Day) }
            Err(ParseInternalError::YMDValueUnset(ymd_unset))
        } else {
            Ok((year.unwrap(), month.unwrap(), day.unwrap()))
        }
    }
}

#[derive(Default, Debug)]
pub struct ParsingResult {
    year: Option<i32>,
    month: Option<i32>,
    day: Option<i32>,
    weekday: Option<bool>,
    hour: Option<i32>,
    minute: Option<i32>,
    second: Option<i32>,
    microsecond: Option<i32>,
    tzname: Option<String>,
    tzoffset: Option<i32>,
    ampm: Option<bool>,
    century_specified: bool,
    any_unused_tokens: Vec<String>,
}

#[derive(Default)]
struct Parser {
    info: ParserInfo,
}

impl Parser {
    pub fn parse(
        &mut self,
        timestr: &str,
        default: Option<NaiveDateTime>,
        ignoretz: bool,
        tzinfos: Vec<String>,
    ) -> Result<(NaiveDateTime, Option<FixedOffset>, Option<Vec<String>>), ParseError> {
        let now = Local::now().naive_local();
        let default_date = default.unwrap_or(now).date();

        let default_ts = NaiveDateTime::new(default_date, NaiveTime::from_hms(0, 0, 0));

        // TODO: What should be done with the tokens?
        let (res, tokens) = self.parse_with_tokens(timestr, None, None, false, false)?;

        let naive = self.build_naive(&res, default_ts);

        if !ignoretz {
            let offset = self.build_tzaware(&naive, &res, default_ts);
            Ok((naive, offset.unwrap(), tokens))
        } else {
            Ok((naive, None, tokens))
        }
    }

    fn parse_with_tokens(
        &mut self,
        timestr: &str,
        dayfirst: Option<bool>,
        yearfirst: Option<bool>,
        fuzzy: bool,
        fuzzy_with_tokens: bool,
    ) -> Result<(ParsingResult, Option<Vec<String>>), ParseError> {
        let fuzzy = if fuzzy_with_tokens { true } else { fuzzy };
        // This is probably a stylistic abomination
        let dayfirst = if let Some(dayfirst) = dayfirst {
            dayfirst
        } else {
            self.info.dayfirst
        };
        let yearfirst = if let Some(yearfirst) = yearfirst {
            yearfirst
        } else {
            self.info.yearfirst
        };

        let mut res = ParsingResult::default();

        let mut l = tokenize(&timestr);
        let mut skipped_idxs: Vec<usize> = Vec::new();

        let mut ymd = YMD::default();

        let len_l = l.len();
        let mut i = 0;

        while i < len_l {
            let value_repr = l[i].clone();

            if let Ok(v) = Decimal::from_str(&value_repr) {
                i = self.parse_numeric_token(&l, i, &self.info, &mut ymd, &mut res, fuzzy)?;
            } else if let Some(value) = self.info.get_weekday(&l[i]) {
                res.weekday = Some(value != 0);
            } else if let Some(value) = self.info.get_month(&l[i]) {
                ymd.append(value as i32, Some(YMDLabel::Month));

                if i + 1 < len_l {
                    if l[i + 1] == "-" || l[i + 1] == "/" {
                        // Jan-01[-99]
                        let sep = &l[i + 1];
                        // TODO: This seems like a very unsafe unwrap
                        ymd.append(l[i + 2].parse::<i32>().unwrap(), None);

                        if i + 3 < len_l && &l[i + 3] == sep {
                            // Jan-01-99
                            ymd.append(l[i + 4].parse::<i32>().unwrap(), None);
                            i += 2;
                        }

                        i += 2;
                    } else if (i + 4 < len_l && l[i + 1] == l[i + 3] && l[i + 3] == " "
                        && self.info.get_pertain(&l[i + 2]))
                    {
                        // Jan of 01
                        if let Some(value) = l[i + 4].parse::<i32>().ok() {
                            let year = self.info.convertyear(value, false);
                            ymd.append(year, Some(YMDLabel::Year));
                        }

                        i += 4;
                    }
                }
            } else if let Some(value) = self.info.get_ampm(&l[i]) {
                let is_ampm = self.ampm_valid(res.hour, res.ampm, fuzzy);

                if is_ampm.is_ok() {
                    res.hour = Some(self.adjust_ampm(res.hour.unwrap(), value));
                    res.ampm = Some(value);
                } else if fuzzy {
                    skipped_idxs.push(i);
                }
            } else if self.could_be_tzname(res.hour, res.tzname.clone(), res.tzoffset, &l[i]) {
                res.tzname = Some(l[i].clone());

                let tzname = res.tzname.clone().unwrap();
                res.tzoffset = self.info.get_tzoffset(&tzname).map(|t| t as i32);

                if i + 1 < len_l && (l[i + 1] == "+" || l[i + 1] == "-") {
                    // GMT+3
                    // According to dateutil docs - reverse the size, as GMT+3 means
                    // "my time +3 is GMT" not "GMT +3 is my time"

                    // TODO: Is there a better way of in-place modifying a vector?
                    let item = if l[i + 1] == "+" {
                        "-".to_owned()
                    } else {
                        "-".to_owned()
                    };
                    l.remove(i + 1);
                    l.insert(i + 1, item);

                    res.tzoffset = None;

                    if self.info.get_utczone(&tzname) {
                        res.tzname = None;
                    }
                }
            } else if res.hour.is_some() && (l[i] == "+" || l[i] == "-") {
                let signal = if l[i] == "+" { 1 } else { -1 };
                let len_li = l[i].len();

                let mut hour_offset: Option<i32> = None;
                let mut min_offset: Option<i32> = None;

                // TODO: check that l[i + 1] is integer?
                if len_li == 4 {
                    // -0300
                    hour_offset = Some(l[i + 1][..2].parse::<i32>().unwrap());
                    min_offset = Some(l[i + 1][2..4].parse::<i32>().unwrap());
                } else if i + 2 < len_l && l[i + 2] == ":" {
                    // -03:00
                    hour_offset = Some(l[i + 1].parse::<i32>().unwrap());
                    min_offset = Some(l[i + 3].parse::<i32>().unwrap());
                    i += 2;
                } else if len_li <= 2 {
                    // -[0]3
                    hour_offset = Some(l[i + 1][..2].parse::<i32>().unwrap());
                    min_offset = Some(0);
                }

                res.tzoffset =
                    Some(signal * (hour_offset.unwrap() * 3600 + min_offset.unwrap() * 60));

                let tzname = res.tzname.clone();
                if i + 5 < len_l && self.info.get_jump(&l[i + 2]) && l[i + 3] == "("
                    && l[i + 5] == ")" && 3 <= l[i + 4].len()
                    && self.could_be_tzname(res.hour, tzname, None, &l[i + 4])
                {
                    // (GMT)
                    res.tzname = Some(l[i + 4].clone());
                    i += 4;
                }

                i += 1;
            } else if !self.info.get_jump(&l[i]) || fuzzy {
                return Err(ParseError::UnrecognizedToken(l[i].clone()));
            } else {
                skipped_idxs.push(i);
            }

            i += 1;
        }

        let (year, month, day) = ymd.resolve_ymd(yearfirst, dayfirst)?;

        res.century_specified = ymd.century_specified;
        res.year = Some(year);
        res.month = Some(month);
        res.day = Some(day);

        if !self.info.validate(&mut res) {
            Err(ParseError::InvalidParseResult(res))
        } else if fuzzy_with_tokens {
            let skipped_tokens = skipped_idxs.into_iter().map(|i| l[i].clone()).collect();
            Ok((res, Some(skipped_tokens)))
        } else {
            Ok((res, None))
        }
    }

    fn could_be_tzname(
        &self,
        hour: Option<i32>,
        tzname: Option<String>,
        tzoffset: Option<i32>,
        token: &str,
    ) -> bool {
        let all_ascii_upper = token == token.to_ascii_uppercase();
        return hour.is_some() && tzname.is_none() && tzoffset.is_none() && token.len() <= 5
            && all_ascii_upper;
    }

    fn ampm_valid(&self, hour: Option<i32>, ampm: Option<bool>, fuzzy: bool) -> ParseResult<bool> {
        if fuzzy && ampm == Some(true) {
            return Ok(false);
        }

        if hour.is_none() {
            if fuzzy {
                Ok(false)
            } else {
                Err(ParseError::AmPmWithoutHour)
            }
        } else if !(0 <= hour.unwrap() && hour.unwrap() <= 12) {
            if fuzzy {
                Ok(false)
            } else {
                Err(ParseError::InvalidHour)
            }
        } else {
            Ok(false)
        }
    }

    fn build_naive(&self, res: &ParsingResult, default: NaiveDateTime) -> NaiveDateTime {
        // TODO: Change month/day to u32
        let d = NaiveDate::from_ymd(
            res.year.unwrap_or(default.year()),
            res.month.unwrap_or(default.month() as i32) as u32,
            res.day.unwrap_or(default.day() as i32) as u32,
        );

        let t = NaiveTime::from_hms_micro(
            res.hour.unwrap_or(default.hour() as i32) as u32,
            res.minute.unwrap_or(default.minute() as i32) as u32,
            res.second.unwrap_or(default.second() as i32) as u32,
            res.microsecond
                .unwrap_or(default.timestamp_subsec_micros() as i32) as u32,
        );

        NaiveDateTime::new(d, t)
    }

    fn build_tzaware(
        &self,
        dt: &NaiveDateTime,
        res: &ParsingResult,
        default: NaiveDateTime,
    ) -> ParseResult<Option<FixedOffset>> {

        if res.tzname.is_none() && res.tzoffset.is_none() {
            Ok(None)
        } else {
            Err(ParseError::TimezoneUnsupported)
        }
    }

    fn parse_numeric_token(
        &self,
        tokens: &Vec<String>,
        idx: usize,
        info: &ParserInfo,
        ymd: &mut YMD,
        res: &mut ParsingResult,
        fuzzy: bool,
    ) -> Result<usize, ParseInternalError> {
        let mut idx = idx;
        let value_repr = &tokens[idx];
        let mut value = Decimal::from_str(&value_repr).unwrap();

        let len_li = value_repr.len();
        let len_l = tokens.len();

        // TODO: I miss the `x in y` syntax
        // TODO: Decompose this logic a bit
        if ymd.len() == 3 && (len_li == 2 || len_li == 4) && res.hour.is_none()
            && (idx + 1 >= len_l
                || (tokens[idx + 1] != ":" && info.get_hms(&tokens[idx + 1]).is_none()))
        {
            // 1990101T32[59]
            let s = &tokens[idx];
            res.hour = s[0..2].parse::<i32>().ok();

            if len_li == 4 {
                res.minute = Some(s[2..4].parse::<i32>()?)
            }
        } else if len_li == 6 || (len_li > 6 && tokens[idx].find(".") == Some(6)) {
            // YYMMDD or HHMMSS[.ss]
            let s = &tokens[idx];

            if ymd.len() == 0 && tokens[idx].find(".") == None {
                ymd.append(s[0..2].parse::<i32>().unwrap(), None);
                ymd.append(s[2..4].parse::<i32>().unwrap(), None);
                ymd.append(s[4..6].parse::<i32>().unwrap(), None);
            } else {
                // 19990101T235959[.59]
                res.hour = s[0..2].parse::<i32>().ok();
                res.minute = s[2..4].parse::<i32>().ok();

                let t = self.parsems(&s[4..])?;
                res.second = Some(t.0);
                res.microsecond = Some(t.1);
            }
        } else if vec![8, 12, 14].contains(&len_li) {
            // YYMMDD
            let s = &tokens[idx];
            ymd.append(s[..4].parse::<i32>().unwrap(), Some(YMDLabel::Year));
            ymd.append(s[4..6].parse::<i32>().unwrap(), None);
            ymd.append(s[6..8].parse::<i32>().unwrap(), None);

            if len_li > 8 {
                res.hour = Some(s[8..10].parse::<i32>()?);
                res.minute = Some(s[10..12].parse::<i32>()?);

                if len_li > 12 {
                    res.second = Some(s[12..].parse::<i32>()?);
                }
            }
        } else if let Some(hms_idx) = self.find_hms_index(idx, tokens, info, true) {
            // HH[ ]h or MM[ ]m or SS[.ss][ ]s
            let (idx, hms) = self.parse_hms(idx, tokens, info, Some(hms_idx));
            if hms.is_some() {
                // TODO: This unwrap is unjustified.
                self.assign_hms(res, value_repr, hms.unwrap());
            }
        } else if idx + 2 < len_l && tokens[idx + 1] == ":" {
            // HH:MM[:SS[.ss]]
            // TODO: Better story around Decimal handling
            res.hour = Some(value.floor().to_i64().unwrap() as i32);
            // TODO: Rescope `value` here?
            value = self.to_decimal(&tokens[idx + 2]);
            let min_sec = self.parse_min_sec(value);
            res.minute = Some(min_sec.0);
            res.second = min_sec.1;

            if idx + 4 < len_l && tokens[idx + 3] == ":" {
                // TODO: (x, y) = (a, b) syntax?
                let ms = self.parsems(&tokens[idx + 4]).unwrap();
                res.second = Some(ms.0);
                res.microsecond = Some(ms.1);

                idx += 2;
            }
            idx += 2;
        } else if idx + 1 < len_l
            && (tokens[idx + 1] == "-" || tokens[idx + 1] == "/" || tokens[idx + 1] == ".")
        {
            // TODO: There's got to be a better way of handling the condition above
            let sep = &tokens[idx + 1];
            ymd.append(value_repr.parse::<i32>().unwrap(), None);

            if idx + 2 < len_l && !info.get_jump(&tokens[idx + 2]) {
                if let Ok(val) = tokens[idx + 2].parse::<i32>() {
                    ymd.append(val, None);
                } else if let Some(val) = info.get_month(&tokens[idx + 2]) {
                    ymd.append(val as i32, Some(YMDLabel::Month));
                }

                if idx + 3 < len_l && &tokens[idx + 3] == sep {
                    if let Some(value) = info.get_month(&tokens[idx + 4]) {
                        ymd.append(value as i32, Some(YMDLabel::Month));
                    } else {
                        ymd.append(tokens[idx + 4].parse::<i32>().unwrap(), None);
                    }

                    idx += 2;
                }

                idx += 1;
            }

            idx += 1
        } else if idx + 1 >= len_l || info.get_jump(&tokens[idx + 1]) {
            if idx + 2 < len_l && info.get_ampm(&tokens[idx + 2]).is_some() {
                let hour = value.to_i64().unwrap() as i32;
                let ampm = info.get_ampm(&tokens[idx + 2]).unwrap();
                res.hour = Some(self.adjust_ampm(hour, ampm));
            } else {
                ymd.append(value.floor().to_i64().unwrap() as i32, None);
            }
        } else if info.get_ampm(&tokens[idx + 1]).is_some()
            && (*ZERO <= value && value < *TWENTY_FOUR)
        {
            // 12am
            let hour = value.to_i64().unwrap() as i32;
            res.hour = Some(self.adjust_ampm(hour, info.get_ampm(&tokens[idx + 1]).unwrap()));
            idx += 1;
        } else if ymd.could_be_day(value.to_i64().unwrap() as i32) {
            ymd.append(value.to_i64().unwrap() as i32, None);
        } else if !fuzzy {
            return Err(ParseInternalError::ValueError("".to_owned()));
        }

        Ok(idx)
    }

    fn adjust_ampm(&self, hour: i32, ampm: bool) -> i32 {
        if hour < 12 && ampm {
            hour + 12
        } else if hour == 12 && ampm {
            0
        } else {
            hour
        }
    }

    fn parsems(&self, seconds_str: &str) -> Result<(i32, i32), ParseInternalError> {
        if seconds_str.contains(".") {
            let split: Vec<&str> = seconds_str.split(".").collect();
            let (i, f): (&str, &str) = (split[0], split[1]);

            let i_parse = i.parse::<i32>()?;
            let f_parse = ljust(f, 6, '0').parse::<i32>()?;
            Ok((i_parse, f_parse))
        } else {
            Ok((seconds_str.parse::<i32>()?, 0))
        }
    }

    fn find_hms_index(
        &self,
        idx: usize,
        tokens: &Vec<String>,
        info: &ParserInfo,
        allow_jump: bool,
    ) -> Option<usize> {
        let len_l = tokens.len();
        let mut hms_idx = None;

        if idx + 1 < len_l && info.get_hms(&tokens[idx + 1]).is_some() {
            hms_idx = Some(idx + 1)
        } else if allow_jump && idx + 2 < len_l && tokens[idx + 1] == " "
            && info.get_hms(&tokens[idx + 2]).is_some()
        {
            hms_idx = Some(idx + 2)
        } else if idx > 0 && info.get_hms(&tokens[idx - 1]).is_some() {
            hms_idx = Some(idx - 1)
        }
        // TODO: The condition for this in Python seems a bit ambiguous
        else if idx == len_l - 1 && tokens[idx - 1] == " "
            && info.get_hms(&tokens[idx - 2]).is_some()
        {
            hms_idx = Some(idx - 2)
        }

        hms_idx
    }

    fn parse_hms(
        &self,
        idx: usize,
        tokens: &Vec<String>,
        info: &ParserInfo,
        hms_index: Option<usize>,
    ) -> (usize, Option<usize>) {
        if hms_index.is_none() {
            (idx, None)
        } else if hms_index.unwrap() > idx {
            (
                hms_index.unwrap(),
                info.get_hms(&tokens[hms_index.unwrap()]),
            )
        } else {
            (
                idx,
                info.get_hms(&tokens[hms_index.unwrap()]).map(|u| u + 1),
            )
        }
    }

    fn assign_hms(&self, res: &mut ParsingResult, value_repr: &str, hms: usize) {
        let value = self.to_decimal(value_repr);

        if hms == 0 {
            res.hour = Some(value.to_i64().unwrap() as i32);
            if close_to_integer(&value) {
                // TODO: High probability of issues with rounding here.
                res.minute = Some((*SIXTY * (value % *ONE)).to_i64().unwrap() as i32);
            }
        } else if hms == 1 {
            let (min, sec) = self.parse_min_sec(value);
        } else if hms == 2 {
            let (sec, micro) = self.parsems(value_repr).unwrap();
        }
    }

    fn to_decimal(&self, value: &str) -> Decimal {
        // TODO: Actual decimals, and handling infinity
        Decimal::from_str(value).unwrap()
    }

    fn parse_min_sec(&self, value: Decimal) -> (i32, Option<i32>) {
        let minute = value.floor().to_i64().unwrap() as i32;
        let mut second = None;

        let sec_remainder = value % *ONE;
        if sec_remainder != *ZERO {
            second = Some((*SIXTY * sec_remainder).floor().to_i64().unwrap() as i32);
        }

        (minute, second)
    }
}

fn close_to_integer(value: &Decimal) -> bool {
    value % *ONE == *ZERO
}

fn ljust(s: &str, chars: usize, replace: char) -> String {
    if s.len() >= chars {
        s[..chars].to_owned()
    } else {
        format!("{}{}", s, replace.to_string().repeat(chars - s.len()))
    }
}

fn parse_with_info(
    timestr: &str,
    info: ParserInfo,
) -> ParseResult<(NaiveDateTime, Option<FixedOffset>, Option<Vec<String>>)> {
    // TODO: Is `::new()` more stylistic?
    let mut parser = Parser { info: info };
    parser.parse(timestr, None, false, vec![])
}

fn parse(timestr: &str) -> ParseResult<(NaiveDateTime, Option<FixedOffset>)> {
    let parse_result = parse_with_info(timestr, ParserInfo::default())?;
    Ok((parse_result.0, parse_result.1))
}