//! `apps.json`: the list of tools, their groups, and the window's preferences.
//!
//! Apps are flat and carry a `group_id` rather than being nested inside their
//! group, so dragging one between groups is a field change instead of a tree
//! rewrite.

use serde::{Deserialize, Serialize};
use std::path::PathBuf;
use url::Url;

use crate::routing::AppScope;

/// What the app claims to be. WebKit's own user agent gets a Google login
/// refused as "not a secure browser", which would make half the list unusable.
pub const CHROME_UA: &str = "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) \
     AppleWebKit/537.36 (KHTML, like Gecko) Chrome/141.0.0.0 Safari/537.36";

#[derive(Debug, Clone, Serialize, Deserialize)]
#[serde(rename_all = "camelCase")]
pub struct App {
    pub id: String,
    pub name: String,
    pub url: String,
    /// Hosts this app owns. Defaults to the URL's exact host — `mail.google.com`
    /// rather than `google.com`, or Gmail and Drive each swallow the other.
    #[serde(default)]
    pub scope: Vec<String>,
    #[serde(default)]
    pub group_id: Option<String>,
    #[serde(default)]
    pub user_agent: Option<String>,
    /// CSS selectors this app hides on every page. Chosen by right-clicking
    /// the thing you never want to see again.
    #[serde(default)]
    pub hidden: Vec<String>,
    /// Page zoom, remembered per app: a dense ERP and a mail client do not
    /// want the same size.
    #[serde(default = "default_zoom")]
    pub zoom: f64,
    #[serde(default)]
    pub order: i32,
}

fn default_zoom() -> f64 {
    1.0
}

impl App {
    pub fn scopes(&self) -> Vec<String> {
        if self.scope.is_empty() {
            default_scope(&self.url).into_iter().collect()
        } else {
            self.scope.clone()
        }
    }

    pub fn ua(&self) -> String {
        self.user_agent.clone().unwrap_or_else(|| CHROME_UA.to_string())
    }
}

#[derive(Debug, Clone, Serialize, Deserialize)]
#[serde(rename_all = "camelCase")]
pub struct Group {
    pub id: String,
    pub name: String,
    #[serde(default)]
    pub collapsed: bool,
    #[serde(default)]
    pub order: i32,
}

#[derive(Debug, Clone, Serialize, Deserialize)]
#[serde(rename_all = "camelCase")]
pub struct Settings {
    #[serde(default)]
    pub nav_collapsed: bool,
    #[serde(default = "default_theme")]
    pub theme: String,
}

fn default_theme() -> String {
    "system".into()
}

impl Default for Settings {
    fn default() -> Self {
        Self {
            nav_collapsed: false,
            theme: default_theme(),
        }
    }
}

#[derive(Debug, Clone, Serialize, Deserialize)]
#[serde(rename_all = "camelCase")]
pub struct Config {
    #[serde(default = "default_version")]
    pub version: u32,
    #[serde(default)]
    pub groups: Vec<Group>,
    #[serde(default)]
    pub apps: Vec<App>,
    #[serde(default)]
    pub settings: Settings,
}

fn default_version() -> u32 {
    1
}

impl Default for Config {
    fn default() -> Self {
        Self {
            version: 1,
            groups: Vec::new(),
            apps: Vec::new(),
            settings: Settings::default(),
        }
    }
}

impl Config {
    /// Scopes in the shape routing wants.
    pub fn scopes(&self) -> Vec<AppScope> {
        self.apps
            .iter()
            .map(|a| AppScope { id: a.id.clone(), scope: a.scopes() })
            .collect()
    }

    pub fn app(&self, id: &str) -> Option<&App> {
        self.apps.iter().find(|a| a.id == id)
    }

    /// Apps in the order the nav shows them: by group, then by position.
    pub fn ordered(&self) -> Vec<&App> {
        let group_rank = |id: &Option<String>| -> i32 {
            match id {
                None => -1,
                Some(g) => self
                    .groups
                    .iter()
                    .find(|x| &x.id == g)
                    .map(|x| x.order)
                    .unwrap_or(i32::MAX),
            }
        };
        let mut apps: Vec<&App> = self.apps.iter().collect();
        apps.sort_by_key(|a| (group_rank(&a.group_id), a.order));
        apps
    }
}

/// The host of a URL, which is the app's scope until the user widens it.
pub fn default_scope(url: &str) -> Option<String> {
    Url::parse(url)
        .ok()
        .and_then(|u| u.host_str().map(|h| h.trim_start_matches("www.").to_string()))
}

/// Normalises what someone types into an app's URL field.
pub fn normalize_url(input: &str) -> String {
    let t = input.trim();
    if t.starts_with("http://") || t.starts_with("https://") {
        t.to_string()
    } else {
        format!("https://{t}")
    }
}

pub fn new_id() -> String {
    uuid::Uuid::new_v4().to_string()
}

/// First-run contents: the tools this was built for.
///
/// Each scope is the exact host, so a link from Gmail to Drive switches rather
/// than being swallowed by whichever Google app happens to be showing. The
/// `/u/N/` paths pin the second Google account, which is the one that matters.
pub fn seed() -> Config {
    let mk = |name: &str, url: &str, group: &str, order: i32| App {
        id: new_id(),
        name: name.into(),
        url: url.into(),
        scope: default_scope(url).into_iter().collect(),
        group_id: Some(group.into()),
        user_agent: None,
        hidden: Vec::new(),
        zoom: 1.0,
        order,
    };
    Config {
        version: 1,
        groups: vec![
            Group { id: "g-work".into(), name: "Work".into(), collapsed: false, order: 0 },
            Group { id: "g-google".into(), name: "Google".into(), collapsed: false, order: 1 },
        ],
        apps: vec![
            mk("Odoo", "https://example.odoo.com/web", "g-work", 0),
            mk("Gmail", "https://mail.google.com/mail/u/N/", "g-google", 0),
            mk("Drive", "https://drive.google.com/drive/u/N/my-drive", "g-google", 1),
            mk("Chat", "https://chat.google.com/u/N/app/home", "g-google", 2),
        ],
        settings: Settings::default(),
    }
}

pub fn config_path(dir: &PathBuf) -> PathBuf {
    dir.join("apps.json")
}

/// Reads `apps.json`, seeding it on first run.
///
/// A file that fails to parse is kept, not replaced: losing someone's app list
/// to a bad write is worse than starting with the seed and telling them.
pub fn load(dir: &PathBuf) -> Result<Config, String> {
    let path = config_path(dir);
    if !path.exists() {
        let cfg = seed();
        save(dir, &cfg)?;
        return Ok(cfg);
    }
    let raw = std::fs::read_to_string(&path).map_err(|e| e.to_string())?;
    serde_json::from_str(&raw).map_err(|e| format!("{} is not readable: {e}", path.display()))
}

pub fn save(dir: &PathBuf, cfg: &Config) -> Result<(), String> {
    std::fs::create_dir_all(dir).map_err(|e| e.to_string())?;
    let json = serde_json::to_string_pretty(cfg).map_err(|e| e.to_string())?;
    std::fs::write(config_path(dir), json).map_err(|e| e.to_string())
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn default_scope_is_the_host_without_www() {
        assert_eq!(default_scope("https://www.google.com/x"), Some("google.com".into()));
        assert_eq!(default_scope("https://mail.google.com"), Some("mail.google.com".into()));
        assert_eq!(default_scope("nonsense"), None);
    }

    #[test]
    fn normalize_url_adds_a_scheme_but_keeps_an_explicit_one() {
        assert_eq!(normalize_url(" github.com "), "https://github.com");
        assert_eq!(normalize_url("http://intranet.local"), "http://intranet.local");
    }

    #[test]
    fn seeded_scopes_are_exact_hosts_that_cannot_swallow_each_other() {
        // The whole point of exact hosts: a Drive link inside Gmail must match
        // Drive, not Gmail. A shared `google.com` scope would break that.
        let cfg = seed();
        let scopes: Vec<String> = cfg.apps.iter().flat_map(|a| a.scopes()).collect();
        assert!(scopes.contains(&"mail.google.com".to_string()));
        assert!(scopes.contains(&"drive.google.com".to_string()));
        assert!(scopes.contains(&"chat.google.com".to_string()));
        assert!(scopes.contains(&"example.odoo.com".to_string()));
        assert!(!scopes.contains(&"google.com".to_string()));
    }

    #[test]
    fn seed_apps_all_carry_a_scope() {
        let cfg = seed();
        assert_eq!(cfg.apps.len(), 4);
        assert!(cfg.apps.iter().all(|a| !a.scopes().is_empty()));
    }

    #[test]
    fn ordering_follows_group_then_position() {
        let cfg = seed();
        let names: Vec<&str> = cfg.ordered().iter().map(|a| a.name.as_str()).collect();
        assert_eq!(names, ["Odoo", "Gmail", "Drive", "Chat"]);
    }

    #[test]
    fn config_survives_a_serde_round_trip() {
        let cfg = seed();
        let json = serde_json::to_string(&cfg).unwrap();
        let back: Config = serde_json::from_str(&json).unwrap();
        assert_eq!(back.apps.len(), cfg.apps.len());
        assert_eq!(back.groups.len(), cfg.groups.len());
    }

    #[test]
    fn a_sparse_file_fills_in_its_defaults() {
        // Hand-edited config files are a supported way to add an app.
        let cfg: Config = serde_json::from_str(
            r#"{"apps":[{"id":"a","name":"X","url":"https://x.com"}]}"#,
        )
        .unwrap();
        assert_eq!(cfg.version, 1);
        assert_eq!(cfg.settings.theme, "system");
        assert_eq!(cfg.apps[0].scopes(), vec!["x.com".to_string()]);
        // A file written before zoom existed must not open every app at 0%.
        assert_eq!(cfg.apps[0].zoom, 1.0);
        assert!(cfg.apps[0].ua().contains("Chrome/"));
    }
}