use lazy_static::lazy_static;
use regex::Regex;
use std::error::Error;
use std::fmt;
use std::result::Result;

pub struct QifFile {
    header: String,
    entries: Vec<QifEntry>,
}

impl QifFile {
    pub fn new(header: String) -> QifFile {
        QifFile {
            header,
            entries: Vec::new(),
        }
    }

    pub fn push(&mut self, entry: QifEntry) {
        if !entry.is_empty() {
            self.entries.push(entry);
        }
    }
}

impl fmt::Display for QifFile {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        let mut hat_separated = String::new();

        for entry in &self.entries {
            hat_separated.push_str("\n");
            hat_separated.push_str(&entry.to_string());
            hat_separated.push_str("\n^");
        }

        write!(f, "{}{}", self.header, hat_separated)
    }
}

pub struct QifEntry {
    date: String,
    amount: String,
    description: String,
}

const DATE_PREFIX: &str = "D";
const AMOUNT_PREFIX: &str = "T";
const DESCRIPTION_PREFIX: &str = "M";

impl QifEntry {
    pub fn new(lines: &Vec<String>) -> Result<QifEntry, QifParsingError> {
        let date = lines.iter().find(|l| l.starts_with(DATE_PREFIX));
        let amount = lines.iter().find(|l| l.starts_with(AMOUNT_PREFIX));
        let description = lines.iter().find(|l| l.starts_with(DESCRIPTION_PREFIX));
        match (date, amount, description) {
            (Some(date), Some(amount), Some(description)) => Ok(QifEntry {
                date: date.chars().skip(1).collect(),
                amount: amount.chars().skip(1).collect(),
                description: description.chars().skip(1).collect(),
            }),
            (None, _, _) => Err(QifParsingError::MissingDate),
            (_, None, _) => Err(QifParsingError::MissingAmount),
            (_, _, None) => Err(QifParsingError::MissingDescription),
        }
    }

    pub fn is_empty(&self) -> bool {
        &self.amount == "0" || &self.amount == "0.00"
    }

    pub fn clean_description(&self) -> String {
        let mut new_description = self.description.clone();
        for algorithm in [
            remove_date,
            remove_card_number,
            replace_common,
            remove_payment_provider,
        ] {
            new_description = algorithm(&new_description);
        }
        new_description
    }
}

impl fmt::Display for QifEntry {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        write!(
            f,
            "{}{}\n{}{}\n{}{}",
            DATE_PREFIX,
            self.date,
            AMOUNT_PREFIX,
            self.amount,
            DESCRIPTION_PREFIX,
            self.clean_description()
        )
    }
}

fn remove_date(text: &str) -> String {
    lazy_static! {
        static ref DATE_REGEX: Regex =
            Regex::new(r"(?i)\d{2} (JAN|FEB|MAR|APR|MAY|JUN|JUL|AUG|SEP|OCT|NOV|DEC)( \d{4})?")
                .unwrap();
    }
    DATE_REGEX.replace_all(text, "").trim().to_string()
}

fn remove_card_number(text: &str) -> String {
    lazy_static! {
        static ref CARD_NUM_REGEX: Regex = Regex::new(r"(\d{6}\*+\d{4}|\d{16})").unwrap();
    }
    CARD_NUM_REGEX.replace_all(text, "").trim().to_string()
}

fn remove_payment_provider(text: &str) -> String {
    lazy_static! {
        static ref PURCH_REGEX: Regex =
            Regex::new(r"(?i)^(purch( payfast\*)?|pp +\*|c\*|yoco +\*|ikh\*)").unwrap();
    }
    PURCH_REGEX.replace_all(text, "").trim().to_string()
}

fn replace_common(text: &str) -> String {
    lazy_static! {
        static ref COMMON_NAMES: Vec<(Regex, &'static str)> = vec!(
            (r"(?i)(pick n pay|pnp)", "Pick n Pay"),
            (r"(?i)checkers", "Checkers"),
            (r"(?i)WOOLWORTHS", "Woolworths"),
            (r"(?i)clicks", "Clicks"),
            (r"(?i)dischem", "Dischem"),
            (r"(?i)spar", "Spar"),
            (r"(?i)(disc memb|disc prem)", "Discovery medical aid"),
            (r"(?i)10XRA", "10X Retirement Annuity"),
            (r"(?i)NEDABF/MFC", "Nedbank MFC"),
            (r"(?i)SARSEFLNG", "SARS Efiling"),
            (r"(?i)Crazy store", "Crazy Store"),
            (r"^PNA", "PNA"),
            (r"^BWH", "Builders Warehouse"),
            (r"^MCD ", "McDonalds"),
            (r"^MRP ", "Mr Price"),
            (r"NakedIn", "Naked Insurance"),
            (r"(?i)sahl", "SA Home Loans"),
            (r"(?i)gautrain", "Gautrain"),
            (r"(?i)BYC DEBIT", "TO SAVINGS POCKET"),
            (r"(?i)AFRIHOST", "Afrihost"),
            (r"(?i)DIALDIRECT", "Dialdirect"),
            (r"(?i)STEERS", "Steers"),
            (r"(?i)CELL C", "Cell C"),
            (r"(?i)ELECTRICITY", "Electricity"),
            (r"(?i)(COUNTRY VIEW|STAR STOP|Shell|Sasol|Engen)", "Petrol"),
            (r"(?i)kung ?-?fu", "Kungfu Kitchen"),
            (r"(?i)^atm cash", "Cash"),
            (r"(?i)DRS CL & ME LA", "Medipark 24")
        )
        .into_iter()
        .map(|(from, to)| (Regex::new(from).unwrap(), to))
        .collect();
    }
    COMMON_NAMES
        .iter()
        .filter_map(|(rule, replacement)| {
            if rule.is_match(text) {
                Some(replacement.to_string())
            } else {
                None
            }
        })
        .next()
        .unwrap_or_else(|| text.to_owned())
        .to_string()
}

#[derive(Debug)]
pub enum QifParsingError {
    MissingDate,
    MissingAmount,
    MissingDescription,
}

impl fmt::Display for QifParsingError {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        write!(f, "{:?}", self)
    }
}

impl Error for QifParsingError {}