use super::{FuzzyMatcher, IndexType, ScoreType};

pub fn cheap_matches(choice: &[char], pattern: &[char], case_sensitive: bool) -> Option<Vec<usize>> {
    let mut first_match_indices = vec![];
    let mut pattern_iter = pattern.iter().peekable();
    for (idx, &c) in choice.iter().enumerate() {
        match pattern_iter.peek() {
            Some(&&p) => {
                if char_equal(c, p, case_sensitive) {
                    first_match_indices.push(idx);
                    let _ = pattern_iter.next();
                }
            }
            None => break,
        }
    }

    if pattern_iter.peek().is_none() {
        Some(first_match_indices)
    } else {
        None
    }
}

/// Given 2 character, check if they are equal (considering ascii case)
/// e.g. ('a', 'A', true) => false
/// e.g. ('a', 'A', false) => true
#[inline]
pub fn char_equal(a: char, b: char, case_sensitive: bool) -> bool {
    if case_sensitive {
        a == b
    } else {
        let a_lower = a.to_lowercase();
        let mut b_lower = b.to_lowercase();
        for a_n in a_lower {
            let Some(b_n) = b_lower.next() else {
                return false;
            };
            if a_n != b_n {
                return false;
            }
        }
        true
    }
}

#[derive(Debug, PartialEq)]
pub enum CharType {
    NonWord,
    Lower,
    Upper,
    Number,
}

#[inline]
pub fn char_type_of(ch: char) -> CharType {
    if ch.is_lowercase() {
        CharType::Lower
    } else if ch.is_uppercase() {
        CharType::Upper
    } else if ch.is_numeric() {
        CharType::Number
    } else {
        CharType::NonWord
    }
}

#[derive(Debug, PartialEq)]
pub enum CharRole {
    Tail,
    Head,
}

// checkout https://github.com/llvm-mirror/clang-tools-extra/blob/master/clangd/FuzzyMatch.cpp
// The Role can be determined from the Type of a character and its neighbors:
//
//   Example  | Chars | Type | Role
//   ---------+--------------+-----
//   F(o)oBar | Foo   | Ull  | Tail
//   Foo(B)ar | oBa   | lUl  | Head
//   (f)oo    | ^fo   | Ell  | Head
//   H(T)TP   | HTT   | UUU  | Tail
//
//      Curr= Empty Lower Upper Separ
// Prev=Empty 0x00, 0xaa, 0xaa, 0xff, // At start, Lower|Upper->Head
// Prev=Lower 0x00, 0x55, 0xaa, 0xff, // In word, Upper->Head;Lower->Tail
// Prev=Upper 0x00, 0x55, 0x59, 0xff, // Ditto, but U(U)U->Tail
// Prev=Separ 0x00, 0xaa, 0xaa, 0xff, // After separator, like at start
pub fn char_role(prev: char, cur: char) -> CharRole {
    use self::CharRole::*;
    use self::CharType::*;
    match (char_type_of(prev), char_type_of(cur)) {
        (Lower, Upper) | (NonWord, Lower) | (NonWord, Upper) => Head,
        _ => Tail,
    }
}

#[allow(dead_code)]
pub fn assert_order(matcher: &dyn FuzzyMatcher, pattern: &str, choices: &[&'static str]) {
    let result = filter_and_sort(matcher, pattern, choices);

    if result != choices {
        // debug print
        println!("pattern: {}", pattern);
        for &choice in choices.iter() {
            if let Some((score, indices)) = matcher.fuzzy_indices(choice, pattern) {
                println!("{}: {:?}", score, wrap_matches(choice, &indices));
            } else {
                println!("NO MATCH for {}", choice);
            }
        }
    }

    assert_eq!(result, choices);
}

#[allow(dead_code)]
pub fn filter_and_sort(matcher: &dyn FuzzyMatcher, pattern: &str, lines: &[&'static str]) -> Vec<&'static str> {
    let mut lines_with_score: Vec<(ScoreType, &'static str)> = lines
        .iter()
        .filter_map(|&s| matcher.fuzzy_match(s, pattern).map(|score| (score, s)))
        .collect();
    lines_with_score.sort_by_key(|(score, _)| -score);
    lines_with_score.into_iter().map(|(_, string)| string).collect()
}

#[allow(dead_code)]
pub fn wrap_matches(line: &str, indices: &[IndexType]) -> String {
    let mut ret = String::new();
    let mut peekable = indices.iter().peekable();
    for (idx, ch) in line.chars().enumerate() {
        let next_id = **peekable.peek().unwrap_or(&&(line.len() as IndexType));
        if next_id == (idx as IndexType) {
            ret.push_str(format!("[{}]", ch).as_str());
            peekable.next();
        } else {
            ret.push(ch);
        }
    }

    ret
}
