// SPDX-License-Identifier: GPL-3.0-only

use cosmic::{
    iced::{advanced::graphics::text::font_system, Point},
    widget::icon,
};
use cosmic_files::mime_icon::{mime_for_path, mime_icon, FALLBACK_MIME_ICON};
use cosmic_text::{Attrs, Buffer, Edit, Shaping, SyntaxEditor, ViEditor, Wrap};
use notify::Watcher;
use std::{
    fs,
    path::PathBuf,
    sync::{Arc, Mutex},
};

use crate::{fl, git::GitDiff, Config, SYNTAX_SYSTEM};

pub enum Tab {
    Editor(EditorTab),
    GitDiff(GitDiffTab),
}

impl Tab {
    pub fn title(&self) -> String {
        match self {
            Self::Editor(tab) => tab.title(),
            Self::GitDiff(tab) => tab.title.clone(),
        }
    }
}

pub struct GitDiffTab {
    pub title: String,
    pub diff: GitDiff,
}

pub struct EditorTab {
    pub path_opt: Option<PathBuf>,
    attrs: Attrs<'static>,
    pub editor: Mutex<ViEditor<'static, 'static>>,
    pub context_menu: Option<Point>,
}

impl EditorTab {
    pub fn new(config: &Config) -> Self {
        //TODO: do not repeat, used in App::init
        let attrs = cosmic_text::Attrs::new().family(cosmic_text::Family::Monospace);

        let mut buffer = Buffer::new_empty(config.metrics());
        buffer.set_text(
            font_system().write().unwrap().raw(),
            "",
            attrs,
            Shaping::Advanced,
        );

        let editor = SyntaxEditor::new(
            Arc::new(buffer),
            SYNTAX_SYSTEM.get().unwrap(),
            config.syntax_theme(),
        )
        .unwrap();

        let mut tab = Self {
            path_opt: None,
            attrs,
            editor: Mutex::new(ViEditor::new(editor)),
            context_menu: None,
        };

        // Update any other config settings
        tab.set_config(config);

        tab
    }

    pub fn set_config(&mut self, config: &Config) {
        let mut editor = self.editor.lock().unwrap();
        let mut font_system = font_system().write().unwrap();
        let mut editor = editor.borrow_with(font_system.raw());
        editor.set_auto_indent(config.auto_indent);
        editor.set_passthrough(!config.vim_bindings);
        editor.set_tab_width(config.tab_width);
        editor.with_buffer_mut(|buffer| {
            buffer.set_wrap(if config.word_wrap {
                Wrap::WordOrGlyph
            } else {
                Wrap::None
            })
        });
        //TODO: dynamically discover light/dark changes
        editor.update_theme(config.syntax_theme());
    }

    pub fn open(&mut self, path: PathBuf) {
        let mut editor = self.editor.lock().unwrap();
        let mut font_system = font_system().write().unwrap();
        let mut editor = editor.borrow_with(font_system.raw());
        match editor.load_text(&path, self.attrs) {
            Ok(()) => {
                log::info!("opened {:?}", path);
                self.path_opt = match fs::canonicalize(&path) {
                    Ok(ok) => Some(ok),
                    Err(err) => {
                        log::error!("failed to canonicalize {:?}: {}", path, err);
                        Some(path)
                    }
                };
            }
            Err(err) => {
                log::error!("failed to open {:?}: {}", path, err);
                self.path_opt = None;
            }
        }
    }

    pub fn reload(&mut self) {
        let mut editor = self.editor.lock().unwrap();
        let mut font_system = font_system().write().unwrap();
        let mut editor = editor.borrow_with(font_system.raw());
        if let Some(path) = &self.path_opt {
            // Save scroll
            let scroll = editor.with_buffer(|buffer| buffer.scroll());
            //TODO: save/restore more?

            match editor.load_text(path, self.attrs) {
                Ok(()) => {
                    log::info!("reloaded {:?}", path);
                }
                Err(err) => {
                    log::error!("failed to reload {:?}: {}", path, err);
                }
            }

            // Restore scroll
            editor.with_buffer_mut(|buffer| buffer.set_scroll(scroll));
        } else {
            log::warn!("tried to reload with no path");
        }
    }

    pub fn save(&mut self) {
        if let Some(path) = &self.path_opt {
            let mut editor = self.editor.lock().unwrap();
            let mut text = String::new();
            editor.with_buffer(|buffer| {
                for line in buffer.lines.iter() {
                    text.push_str(line.text());
                    text.push('\n');
                }
            });
            match fs::write(path, text) {
                Ok(()) => {
                    editor.set_changed(false);
                    log::info!("saved {:?}", path);
                }
                Err(err) => {
                    log::error!("failed to save {:?}: {}", path, err);
                }
            }
        } else {
            log::warn!("tab has no path yet");
        }
    }

    pub fn watch(&self, watcher_opt: &mut Option<notify::RecommendedWatcher>) {
        if let Some(path) = &self.path_opt {
            if let Some(watcher) = watcher_opt {
                match watcher.watch(path, notify::RecursiveMode::NonRecursive) {
                    Ok(()) => {
                        log::info!("watching {:?} for changes", path);
                    }
                    Err(err) => {
                        log::warn!("failed to watch {:?} for changes: {:?}", path, err);
                    }
                }
            }
        }
    }

    pub fn changed(&self) -> bool {
        let editor = self.editor.lock().unwrap();
        editor.changed()
    }

    pub fn icon(&self, size: u16) -> icon::Icon {
        match &self.path_opt {
            Some(path) => icon::icon(mime_icon(mime_for_path(path), size)).size(size),
            None => icon::from_name(FALLBACK_MIME_ICON).size(size).icon(),
        }
    }

    pub fn title(&self) -> String {
        //TODO: show full title when there is a conflict
        if let Some(path) = &self.path_opt {
            match path.file_name() {
                Some(file_name_os) => match file_name_os.to_str() {
                    Some(file_name) => match file_name {
                        "mod.rs" => title_with_parent(path, file_name),
                        _ => file_name.to_string(),
                    },
                    None => format!("{}", path.display()),
                },
                None => format!("{}", path.display()),
            }
        } else {
            fl!("new-document")
        }
    }

    pub fn replace(&self, value: &str, replace: &str) -> bool {
        let mut editor = self.editor.lock().unwrap();
        let mut cursor = editor.cursor();
        let start_line = cursor.line;
        while cursor.line < editor.with_buffer(|buffer| buffer.lines.len()) {
            if let Some(index) = editor.with_buffer(|buffer| {
                buffer.lines[cursor.line]
                    .text()
                    .match_indices(value)
                    .filter_map(|(i, _)| {
                        if cursor.line != start_line || i >= cursor.index {
                            Some(i)
                        } else {
                            None
                        }
                    })
                    .next()
            }) {
                cursor.index = index;
                let mut end = cursor;
                end.index = index + value.len();

                editor.start_change();
                editor.delete_range(cursor, end);
                cursor = editor.insert_at(cursor, replace, None);
                editor.set_cursor(cursor);
                editor.finish_change();

                return true;
            }

            cursor.line += 1;
        }
        false
    }

    // Code adapted from cosmic-text ViEditor search
    pub fn search(&self, value: &str, forwards: bool) -> bool {
        let mut editor = self.editor.lock().unwrap();
        let mut cursor = editor.cursor();
        let start_line = cursor.line;
        if forwards {
            while cursor.line < editor.with_buffer(|buffer| buffer.lines.len()) {
                if let Some(index) = editor.with_buffer(|buffer| {
                    buffer.lines[cursor.line]
                        .text()
                        .match_indices(value)
                        .filter_map(|(i, _)| {
                            if cursor.line != start_line || i > cursor.index {
                                Some(i)
                            } else {
                                None
                            }
                        })
                        .next()
                }) {
                    cursor.index = index;
                    editor.set_cursor(cursor);
                    return true;
                }

                cursor.line += 1;
            }
        } else {
            cursor.line += 1;
            while cursor.line > 0 {
                cursor.line -= 1;

                if let Some(index) = editor.with_buffer(|buffer| {
                    buffer.lines[cursor.line]
                        .text()
                        .rmatch_indices(value)
                        .filter_map(|(i, _)| {
                            if cursor.line != start_line || i < cursor.index {
                                Some(i)
                            } else {
                                None
                            }
                        })
                        .next()
                }) {
                    cursor.index = index;
                    editor.set_cursor(cursor);
                    return true;
                }
            }
        }
        false
    }
}

/// Includes parent name in tab title
///
/// Useful for distinguishing between Rust modules named `mod.rs`
fn title_with_parent(path: &std::path::Path, file_name: &str) -> String {
    let parent_name = path
        .parent()
        .and_then(|path| path.file_name())
        .and_then(|os_str| os_str.to_str());

    match parent_name {
        Some(parent) => [parent, "/", file_name].concat(),
        None => file_name.to_string(),
    }
}