use std::path::{Path, PathBuf};

use fuzzy::StringMatch;
use gpui::{
    elements::{Label, LabelStyle},
    Element, ElementBox,
};
use workspace::WorkspaceLocation;

pub struct HighlightedText {
    pub text: String,
    pub highlight_positions: Vec<usize>,
    char_count: usize,
}

impl HighlightedText {
    fn join(components: impl Iterator<Item = Self>, separator: &str) -> Self {
        let mut char_count = 0;
        let separator_char_count = separator.chars().count();
        let mut text = String::new();
        let mut highlight_positions = Vec::new();
        for component in components {
            if char_count != 0 {
                text.push_str(separator);
                char_count += separator_char_count;
            }

            highlight_positions.extend(
                component
                    .highlight_positions
                    .iter()
                    .map(|position| position + char_count),
            );
            text.push_str(&component.text);
            char_count += component.text.chars().count();
        }

        Self {
            text,
            highlight_positions,
            char_count,
        }
    }

    pub fn render(self, style: impl Into<LabelStyle>) -> ElementBox {
        Label::new(self.text, style)
            .with_highlights(self.highlight_positions)
            .boxed()
    }
}

pub struct HighlightedWorkspaceLocation {
    pub names: HighlightedText,
    pub paths: Vec<HighlightedText>,
}

impl HighlightedWorkspaceLocation {
    pub fn new(string_match: &StringMatch, location: &WorkspaceLocation) -> Self {
        let mut path_start_offset = 0;
        let (names, paths): (Vec<_>, Vec<_>) = location
            .paths()
            .iter()
            .map(|path| {
                let mut full_path = PathBuf::new();
                if path.starts_with(util::paths::HOME.as_path()) {
                    full_path.push("~");
                    full_path.push(path.strip_prefix(util::paths::HOME.as_path()).unwrap());
                } else {
                    full_path.push(path)
                }

                let highlighted_text = Self::highlights_for_path(
                    full_path.as_ref(),
                    &string_match.positions,
                    path_start_offset,
                );

                path_start_offset += highlighted_text.1.char_count;

                highlighted_text
            })
            .unzip();

        Self {
            names: HighlightedText::join(names.into_iter().filter_map(|name| name), ", "),
            paths,
        }
    }

    // Compute the highlighted text for the name and path
    fn highlights_for_path(
        path: &Path,
        match_positions: &Vec<usize>,
        path_start_offset: usize,
    ) -> (Option<HighlightedText>, HighlightedText) {
        let path_string = path.to_string_lossy();
        let path_char_count = path_string.chars().count();
        // Get the subset of match highlight positions that line up with the given path.
        // Also adjusts them to start at the path start
        let path_positions = match_positions
            .iter()
            .copied()
            .skip_while(|position| *position < path_start_offset)
            .take_while(|position| *position < path_start_offset + path_char_count)
            .map(|position| position - path_start_offset)
            .collect::<Vec<_>>();

        // Again subset the highlight positions to just those that line up with the file_name
        // again adjusted to the start of the file_name
        let file_name_text_and_positions = path.file_name().map(|file_name| {
            let text = file_name.to_string_lossy();
            let char_count = text.chars().count();
            let file_name_start = path_char_count - char_count;
            let highlight_positions = path_positions
                .iter()
                .copied()
                .skip_while(|position| *position < file_name_start)
                .take_while(|position| *position < file_name_start + char_count)
                .map(|position| position - file_name_start)
                .collect::<Vec<_>>();
            HighlightedText {
                text: text.to_string(),
                highlight_positions,
                char_count,
            }
        });

        (
            file_name_text_and_positions,
            HighlightedText {
                text: path_string.to_string(),
                highlight_positions: path_positions,
                char_count: path_char_count,
            },
        )
    }
}