//! The Characters window: the project's cast, where each of them appears, and
//! keeping the summary grid in step with the sheets.

use super::*;

impl App {
    /// (Re)read the project's character sheets.
    pub(super) fn load_characters(&mut self) {
        self.characters = match self.characters_dir() {
            Some(dir) => crate::characters::read_sheets(&dir, &self.config.draft_marker),
            None => Vec::new(),
        };
    }

    /// Manuscript files whose `Characters:` line names `character`, as
    /// workspace-relative paths.
    ///
    /// This is the continuity question the app can answer that a folder of
    /// markdown cannot: once a draft is long, "which scenes is she actually in?"
    /// stops being answerable from memory.
    pub(super) fn scenes_with(&self, character: &crate::characters::Character) -> Vec<String> {
        self.files
            .iter()
            .filter(|name| self.is_manuscript(name))
            .filter(|name| {
                let Some(text) = std::fs::read_to_string(self.path_for(name)).ok() else {
                    return false;
                };
                let Some(line) =
                    crate::preprocess::field(&text, &self.config.draft_marker, "Characters")
                else {
                    return false;
                };
                crate::preprocess::value_items(&line)
                    .iter()
                    .any(|mention| character.is_named_by(mention))
            })
            .cloned()
            .collect()
    }

    /// Write the generated character grid over the project's grid file.
    fn regenerate_character_grid(&mut self) {
        let Some(dir) = self.characters_dir() else {
            self.status = "No character folder found near this workspace".to_string();
            return;
        };
        let markdown = crate::characters::grid_markdown(&self.characters);
        // Reuse the grid file the project already has, wherever it sits.
        let existing = crate::characters::grid_file(&dir);
        let path = existing.unwrap_or_else(|| dir.join("character_grid").join("character_grid.md"));
        if let Some(parent) = path.parent() {
            if let Err(e) = std::fs::create_dir_all(parent) {
                self.status = format!("Could not write the grid: {e}");
                return;
            }
        }
        match std::fs::write(&path, markdown) {
            Ok(_) => {
                self.status = format!(
                    "Wrote {} character(s) to {}",
                    self.characters.len(),
                    path.display()
                );
                // The grid may be one of the workspace's own files.
                self.file_meta = self.snapshot_file_meta();
            }
            Err(e) => self.status = format!("Could not write the grid: {e}"),
        }
    }

    /// The Characters window.
    pub(super) fn characters_window(&mut self, ctx: &egui::Context) {
        let mut open = self.show_characters;
        let mut close = false;
        let mut regenerate = false;
        let mut reload = false;
        // A scene or sheet the user asked to open, as a workspace-relative path.
        let mut open_file: Option<String> = None;

        egui::Window::new("Characters")
            .open(&mut open)
            .resizable(true)
            .collapsible(false)
            .default_width(420.0)
            .show(ctx, |ui| {
                match self.characters_dir() {
                    Some(dir) => {
                        ui.label(
                            egui::RichText::new(format!("Sheets in {}", dir.display()))
                                .small()
                                .weak(),
                        );
                    }
                    None => {
                        ui.label(
                            egui::RichText::new(
                                "No character folder found near this workspace.",
                            )
                            .weak(),
                        );
                    }
                }
                ui.horizontal(|ui| {
                    if ui.button("⟳ Reload sheets").clicked() {
                        reload = true;
                    }
                    if ui
                        .add_enabled(
                            !self.characters.is_empty(),
                            egui::Button::new("▦ Rebuild grid"),
                        )
                        .on_hover_text(
                            "Regenerate the character grid from the sheets, replacing \
                             whatever is in it",
                        )
                        .clicked()
                    {
                        regenerate = true;
                    }
                });
                ui.separator();

                if self.characters.is_empty() {
                    ui.label(egui::RichText::new("No character sheets read yet.").weak());
                }

                egui::ScrollArea::vertical()
                    .auto_shrink([false, true])
                    .max_height(420.0)
                    .show(ui, |ui| {
                        for character in &self.characters {
                            let scenes = self.scenes_with(character);
                            let header = format!(
                                "{}  ({} scene{})",
                                character.name,
                                scenes.len(),
                                if scenes.len() == 1 { "" } else { "s" }
                            );
                            egui::CollapsingHeader::new(header)
                                .id_salt(&character.name)
                                .show(ui, |ui| {
                                    if let Some(tagline) = character.tagline() {
                                        ui.label(egui::RichText::new(tagline).italics().weak());
                                    }
                                    if ui.link("open sheet").clicked() {
                                        if let Some(rel) = self.relative_to_workspace(
                                            &character.file,
                                        ) {
                                            open_file = Some(rel);
                                        }
                                    }
                                    if scenes.is_empty() {
                                        ui.label(
                                            egui::RichText::new(
                                                "Not named in any scene's Characters: line.",
                                            )
                                            .small()
                                            .weak(),
                                        );
                                    }
                                    for scene in &scenes {
                                        if ui.link(scene).clicked() {
                                            open_file = Some(scene.clone());
                                        }
                                    }
                                });
                        }
                    });

                ui.separator();
                if ui.button("Close").clicked() {
                    close = true;
                }
            });

        if reload {
            self.load_characters();
        }
        if regenerate {
            self.regenerate_character_grid();
        }
        if let Some(path) = open_file {
            if let Some(idx) = self.files.iter().position(|f| *f == path) {
                self.select(idx);
            } else {
                self.status = format!("{path} is not in this workspace");
            }
        }
        self.show_characters = open && !close;
    }

    /// Express an absolute path as workspace-relative, if it is inside.
    pub(super) fn relative_to_workspace(&self, path: &Path) -> Option<String> {
        path.strip_prefix(self.workspace())
            .ok()?
            .to_str()
            .map(|s| s.replace('\\', "/"))
    }
}