use crate::defines::{LiteralFloat, LiteralInt};
use crate::parsing::lex_tokens::LexToken;
use itertools::MultiPeek;
use std::str::Chars;

#[inline(always)]
fn get_decimal_value(c: char) -> Option<LiteralInt> {
    match c {
        '0' => Some(0),
        '1' => Some(1),
        '2' => Some(2),
        '3' => Some(3),
        '4' => Some(4),
        '5' => Some(5),
        '6' => Some(6),
        '7' => Some(7),
        '8' => Some(8),
        '9' => Some(9),
        _ => None,
    }
}

#[inline(always)]
fn lex_numeric_default(chars: &mut MultiPeek<Chars>) -> LexToken {
    let mut int_value: LiteralInt = 0;
    let mut decimal_value: LiteralInt = 0;
    let mut exponent_value: LiteralInt = 0;
    let mut decimal_length: LiteralInt = 0;
    let mut is_decimal = false;
    let mut is_exponent = false;
    let mut is_reading = true;

    let mut c: Option<char> = chars.peek().cloned();
    while c.is_some() && is_reading {
        let v = get_decimal_value(c.unwrap());
        match v {
            None => {
                if c.unwrap() == '_' {
                    chars.next();
                    c = chars.peek().cloned();
                    continue;
                }
                if !is_decimal && c.unwrap() == '.' {
                    is_decimal = true;
                    chars.next();
                    c = chars.peek().cloned();
                    continue;
                }
                if is_decimal && c.unwrap() == 'e' || c.unwrap() == 'E' {
                    is_decimal = false;
                    is_exponent = true;
                    chars.next();
                    c = chars.peek().cloned();
                    continue;
                }
                c = chars.peek().cloned();
                is_reading = false;
                continue;
            }
            Some(i) => {
                chars.next();
                if is_decimal {
                    decimal_value *= 10;
                    decimal_value += i;
                    decimal_length += 1;
                } else if is_exponent {
                    exponent_value *= 10;
                    exponent_value += i;
                } else {
                    int_value *= 10;
                    int_value += i;
                }
            }
        }
        c = chars.peek().cloned();
    }
    chars.reset_peek();
    if is_decimal || is_exponent {
        let mut val = int_value as LiteralFloat
            + (decimal_value as LiteralFloat / 10_i64.pow(decimal_length as u32) as LiteralFloat);
        if is_exponent {
            val *= exponent_value.pow(10) as LiteralFloat;
        }
        LexToken::FloatLiteral(val)
    } else {
        LexToken::IntegerLiteral(int_value)
    }
}

#[inline(always)]
fn get_hexadecimal_value(c: char) -> Option<LiteralInt> {
    match c {
        '0' => Some(0),
        '1' => Some(1),
        '2' => Some(2),
        '3' => Some(3),
        '4' => Some(4),
        '5' => Some(5),
        '6' => Some(6),
        '7' => Some(7),
        '8' => Some(8),
        '9' => Some(9),
        'A' | 'a' => Some(10),
        'B' | 'b' => Some(11),
        'C' | 'c' => Some(12),
        'D' | 'd' => Some(13),
        'E' | 'e' => Some(14),
        'F' | 'f' => Some(15),
        _ => None,
    }
}

#[inline(always)]
fn lex_numeric_hexadecimal(chars: &mut MultiPeek<Chars>) -> LexToken {
    let mut int_value: LiteralInt = 0;
    let mut reading = true;
    let mut n = chars.peek().cloned();
    while n.is_some() && reading {
        match get_hexadecimal_value(n.unwrap()) {
            Some(i) => {
                int_value <<= 4;
                int_value += i;
                chars.next();
            }
            None => {
                if n.unwrap() == '_' {
                    chars.next();
                } else {
                    reading = false
                }
            }
        }
        n = chars.peek().cloned();
    }
    LexToken::IntegerLiteral(int_value)
}

#[inline(always)]
fn get_octal_value(c: char) -> Option<LiteralInt> {
    match c {
        '0' => Some(0),
        '1' => Some(1),
        '2' => Some(2),
        '3' => Some(3),
        '4' => Some(4),
        '5' => Some(5),
        '6' => Some(6),
        '7' => Some(7),
        _ => None,
    }
}

#[inline(always)]
fn lex_numeric_octal(chars: &mut MultiPeek<Chars>) -> LexToken {
    let mut int_value: LiteralInt = 0;
    let mut reading = true;
    let mut n = chars.peek().cloned();
    while n.is_some() && reading {
        match get_octal_value(n.unwrap()) {
            Some(i) => {
                int_value <<= 3;
                int_value += i;
                chars.next();
            }
            None => {
                if n.unwrap() == '_' {
                    chars.next();
                } else {
                    reading = false
                }
            }
        }
        n = chars.peek().cloned();
    }
    LexToken::IntegerLiteral(int_value)
}

#[inline(always)]
fn get_binary_value(c: char) -> Option<LiteralInt> {
    match c {
        '0' => Some(0),
        '1' => Some(1),
        _ => None,
    }
}

#[inline(always)]
fn lex_numeric_binary(chars: &mut MultiPeek<Chars>) -> LexToken {
    let mut int_value: LiteralInt = 0;
    let mut reading = true;
    let mut n = chars.peek().cloned();
    while n.is_some() && reading {
        match get_binary_value(n.unwrap()) {
            Some(i) => {
                int_value <<= 1;
                int_value += i;
                chars.next();
            }
            None => {
                if n.unwrap() == '_' {
                    chars.next();
                } else {
                    reading = false
                }
            }
        }
        n = chars.peek().cloned();
    }
    LexToken::IntegerLiteral(int_value)
}

#[inline(always)]
pub fn lex_numeric(chars: &mut MultiPeek<Chars>) -> LexToken {
    chars.reset_peek();
    if chars.peek() == Some(&'0') {
        match chars.peek() {
            Some(&'D') | Some(&'d') => {
                chars.next();
                chars.next();
                return lex_numeric_default(chars);
            }
            Some(&'X') | Some(&'x') => {
                chars.next();
                chars.next();
                return lex_numeric_hexadecimal(chars);
            }
            Some(&'O') | Some(&'o') => {
                chars.next();
                chars.next();
                return lex_numeric_octal(chars);
            }
            Some(&'B') | Some(&'b') => {
                chars.next();
                chars.next();
                return lex_numeric_binary(chars);
            }
            _ => {}
        }
    }
    chars.reset_peek();
    lex_numeric_default(chars)
}