use crate::highlighting;
use crate::HighlightingOptions;
use crate::SearchDirection;
use std::cmp;
use termion::color;
use unicode_segmentation::UnicodeSegmentation;

#[derive(Default)]
pub struct Row {
    string: String,
    highlighting: Vec<highlighting::Type>,
    len: usize,
}

impl From<&str> for Row {
    fn from(slice: &str) -> Self {
        Self {
            string: String::from(slice),
            highlighting: Vec::new(),
            len: slice.graphemes(true).count(),
        }
    }
}

impl Row {
    pub fn render(&self, start: usize, end: usize) -> String {
        let end = cmp::min(end, self.string.len());
        let start = cmp::min(start, end);

        let mut result = String::new();
        let mut current_highlighting = &highlighting::Type::None;

        #[allow(clippy::integer_arithmetic)]
        for (index, grapheme) in self.string[..]
            .graphemes(true)
            .enumerate()
            .skip(start)
            .take(end - start)
        {
            if let Some(c) = grapheme.chars().next() {
                let highlighting_type = self
                    .highlighting
                    .get(index)
                    .unwrap_or(&highlighting::Type::None);

                if highlighting_type != current_highlighting {
                    current_highlighting = highlighting_type;

                    let start_highlight =
                        format!("{}", termion::color::Fg(highlighting_type.to_color()));

                    result.push_str(&start_highlight[..]);
                }

                if c == '\t' {
                    result.push_str("    ");
                } else {
                    result.push(c);
                }
            }
        }

        let end_highlight = format!("{}", termion::color::Fg(color::Reset));
        result.push_str(&end_highlight[..]);

        result
    }

    pub fn len(&self) -> usize {
        self.len
    }

    pub fn is_empty(&self) -> bool {
        self.len == 0
    }

    pub fn insert(&mut self, at: usize, c: char) {
        if at >= self.len() {
            self.string.push(c);
            self.len += 1;

            return;
        }

        let mut result = String::new();
        let mut length = 0;

        for (index, grapheme) in self.string[..].graphemes(true).enumerate() {
            length += 1;

            if index == at {
                length += 1;
                result.push(c);
            }

            result.push_str(grapheme);
        }

        self.len = length;
        self.string = result;
    }

    #[allow(clippy::integer_arithmetic)]
    pub fn delete(&mut self, at: usize) {
        if at >= self.len() {
            return;
        }

        let mut result = String::new();
        let mut length = 0;

        for (index, grapheme) in self.string[..].graphemes(true).enumerate() {
            if index != at {
                length += 1;
                result.push_str(grapheme);
            }
        }

        self.len = length;
        self.string = result;
    }

    pub fn append(&mut self, new: &Self) {
        self.string = format!("{}{}", self.string, new.string);
        self.len += new.len;
    }

    pub fn split(&mut self, at: usize) -> Self {
        let mut row = String::new();
        let mut length = 0;
        let mut splitted_row = String::new();
        let mut splittend_length = 0;

        for (index, grapheme) in self.string[..].graphemes(true).enumerate() {
            if index < at {
                length += 1;
                row.push_str(grapheme);
            } else {
                splittend_length += 1;
                splitted_row.push_str(grapheme);
            }
        }

        self.string = row;
        self.len = length;

        Self {
            string: splitted_row,
            len: splittend_length,
            highlighting: Vec::new(),
        }
    }

    pub fn as_bytes(&self) -> &[u8] {
        self.string.as_bytes()
    }

    pub fn find(&self, query: &str, at: usize, direction: SearchDirection) -> Option<usize> {
        if at > self.len || query.is_empty() {
            return None;
        }

        let (start, end) = match direction {
            SearchDirection::Forward => (at, self.len),
            SearchDirection::Backward => (0, at),
        };

        let substring: String = self.string[..]
            .graphemes(true)
            .skip(start)
            .take(end - start)
            .collect();

        let matching_byte_index = if direction == SearchDirection::Forward {
            substring.find(query)
        } else {
            substring.rfind(query)
        };

        if let Some(matching_byte_index) = matching_byte_index {
            for (grapheme_index, (byte_index, _)) in
                substring[..].grapheme_indices(true).enumerate()
            {
                if matching_byte_index == byte_index {
                    return Some(start + grapheme_index);
                }
            }
        }

        None
    }

    pub fn highlight(&mut self, opts: HighlightingOptions, word: Option<&str>) {
        let mut highlighting = Vec::new();
        let chars: Vec<char> = self.string.chars().collect();
        let mut matches = Vec::new();
        let mut search_index = 0;

        if let Some(word) = word {
            while let Some(search_match) = self.find(word, search_index, SearchDirection::Forward) {
                matches.push(search_match);

                if let Some(next_index) = search_match.checked_add(word[..].graphemes(true).count())
                {
                    search_index = next_index
                } else {
                    break;
                }
            }
        }

        let mut prev_is_separator = true;
        let mut in_string = false;
        let mut index = 0;
        while let Some(c) = chars.get(index) {
            if let Some(word) = word {
                if matches.contains(&index) {
                    for _ in word[..].graphemes(true) {
                        index += 1;
                        highlighting.push(highlighting::Type::Match);
                    }

                    continue;
                }
            }

            let previous_highlight = if index > 0 {
                highlighting
                    .get(index - 1)
                    .unwrap_or(&highlighting::Type::None)
            } else {
                &highlighting::Type::None
            };

            if opts.characters() && !in_string && *c == '\'' {
                prev_is_separator = true;

                if let Some(next_char) = chars.get(index.saturating_add(1)) {
                    let closing_index = if *next_char == '\\' {
                        index.saturating_add(3)
                    } else {
                        index.saturating_add(2)
                    };

                    if let Some(closing_char) = chars.get(closing_index) {
                        if *closing_char == '\'' {
                            for _ in 0..=closing_index.saturating_sub(index) {
                                highlighting.push(highlighting::Type::Character);
                                index += 1;
                            }

                            continue;
                        }
                    }
                }

                highlighting.push(highlighting::Type::None);
                index += 1;
                continue;
            }

            if opts.strings() {
                if in_string {
                    highlighting.push(highlighting::Type::String);

                    // Don't let an escaped character stop string highlighting
                    if *c == '\\' && index < self.len().saturating_sub(1) {
                        highlighting.push(highlighting::Type::String);
                        index += 2;
                        continue;
                    }

                    if *c == '"' {
                        in_string = false;
                        prev_is_separator = true;
                    } else {
                        prev_is_separator = false;
                    }

                    index += 1;
                    continue;
                } else if prev_is_separator && *c == '"' {
                    highlighting.push(highlighting::Type::String);

                    in_string = true;
                    prev_is_separator = true;
                    index += 1;
                    continue;
                }
            }

            if opts.comments() && *c == '/' {
                if let Some(next_char) = chars.get(index.saturating_add(1)) {
                    if *next_char == '/' {
                        for _ in index..chars.len() {
                            highlighting.push(highlighting::Type::Comment);
                        }

                        break;
                    }
                };
            }

            if opts.numbers() {
                if (c.is_ascii_digit()
                    && (prev_is_separator || *previous_highlight == highlighting::Type::Number))
                    || (*c == '.' && *previous_highlight == highlighting::Type::Number)
                {
                    highlighting.push(highlighting::Type::Number)
                } else {
                    highlighting.push(highlighting::Type::None)
                }
            } else {
                highlighting.push(highlighting::Type::None)
            }

            prev_is_separator = c.is_ascii_punctuation() || c.is_ascii_whitespace();
            index += 1;
        }

        self.highlighting = highlighting;
    }
}