//! Settings backup, native side ([`crate::commands::BACKUP`], served for every app; an app that
//! does not use them grants them to no one): everything the owner set up in one versioned `.waybetter` file.
//! Every command is shell-only. The envelope, the secret scrubbing and the validation are
//! [`crate::backup`]'s; this module asks for what to save and writes the file.
//!
//! What a backup carries is the app's: its native sections
//! ([`crate::app::SiteHooks::backup_sections`]), its drafts only when the owner ticks "include
//! drafts" ([`crate::app::SiteHooks::backup_drafts`]) and the shell's own storage (`decks`,
//! `shell`). Importing shows the sections for a preview first (nothing is applied); the app applies
//! the ones the owner chose ([`crate::app::SiteHooks::backup_apply`]), each checked as its own
//! setter checks it. Never included: cookies, WebView profile folders, the session database,
//! tokens, signing keys, the sync key, update state, font files, gallery and clipboard data.

use crate::app::{config, hooks, tr};
use crate::backup;
use crate::host::shell_only;
use serde::Serialize;
use serde_json::{json, Map, Value};
use tauri::{AppHandle, Webview};
use tauri_plugin_dialog::DialogExt;

/// The app's native sections (plus drafts when asked) and `extra` sections from the shell
/// (`decks`), secret-looking keys removed.
fn collect(app: &AppHandle, include_drafts: bool, extra: Option<Map<String, Value>>) -> Result<Map<String, Value>, String> {
    let hooks = hooks(app);
    let mut sections = hooks.backup_sections(app)?;
    if include_drafts {
        if let Some(drafts) = hooks.backup_drafts(app)? {
            sections.insert("drafts".into(), drafts);
        }
    }
    for (key, value) in extra.unwrap_or_default() {
        // The shell only adds its own storage; it cannot replace a native section or add drafts.
        if (key == "decks" || key == "shell") && value.is_object() {
            sections.insert(key, value);
        }
    }
    let mut value = Value::Object(sections);
    backup::strip_secrets(&mut value);
    Ok(match value {
        Value::Object(map) => map,
        _ => Map::new(),
    })
}

fn envelope(app: &AppHandle, sections: Map<String, Value>) -> Value {
    json!({
        "format": backup::FORMAT,
        "version": backup::VERSION,
        "app": config(app).title,
        "appVersion": app.package_info().version.to_string(),
        "createdAt": chrono::Utc::now().to_rfc3339_opts(chrono::SecondsFormat::Millis, true),
        "includesDrafts": sections.contains_key("drafts"),
        "sections": sections,
    })
}

/// The current settings as a backup would carry them (for the import preview's diff).
#[tauri::command]
pub(crate) async fn backup_collect(webview: Webview, app: AppHandle, include_drafts: bool) -> Result<Map<String, Value>, String> {
    shell_only(&webview)?;
    collect(&app, include_drafts, None)
}

/// Asks where to save and writes the `.waybetter` file. Returns the path, or None when cancelled.
#[tauri::command]
pub(crate) async fn backup_export_file(
    webview: Webview,
    app: AppHandle,
    include_drafts: bool,
    extra: Option<Map<String, Value>>,
) -> Result<Option<String>, String> {
    shell_only(&webview)?;
    let sections = collect(&app, include_drafts, extra)?;
    let bytes = serde_json::to_vec_pretty(&envelope(&app, sections)).map_err(|_| "BACKUP: serialization failed")?;
    let today = chrono::Utc::now().format("%Y-%m-%d");
    let name = format!("wayBetter-settings-{today}.{}", backup::EXTENSION);
    let picked = app
        .dialog()
        .file()
        .set_parent(&webview.window())
        .set_title(tr(&app, "native.dialog.saveBackup", "Save wayBetter settings"))
        .set_file_name(&name)
        .add_filter(tr(&app, "native.dialog.backupFilter", "wayBetter settings"), &[backup::EXTENSION])
        .blocking_save_file();
    let Some(picked) = picked else { return Ok(None) };
    let mut path = picked.into_path().map_err(|_| "BACKUP: not a local file")?;
    if path.extension().and_then(|ext| ext.to_str()) != Some(backup::EXTENSION) {
        path.set_extension(backup::EXTENSION);
    }
    backup::write_atomic(&path, &bytes)?;
    Ok(Some(path.to_string_lossy().into_owned()))
}

#[derive(Serialize)]
#[serde(rename_all = "camelCase")]
pub(crate) struct OpenedBackup {
    file: String,
    created_at: Option<String>,
    app_version: Option<String>,
    sections: Map<String, Value>,
}

/// Asks for a `.waybetter` file and returns its sections for the preview (nothing applied yet).
#[tauri::command]
pub(crate) async fn backup_open_file(webview: Webview, app: AppHandle) -> Result<Option<OpenedBackup>, String> {
    shell_only(&webview)?;
    let picked = app
        .dialog()
        .file()
        .set_parent(&webview.window())
        .set_title(tr(&app, "native.dialog.importBackup", "Import wayBetter settings"))
        .add_filter(tr(&app, "native.dialog.backupFilter", "wayBetter settings"), &[backup::EXTENSION, "json"])
        .blocking_pick_file();
    let Some(picked) = picked else { return Ok(None) };
    let path = picked.into_path().map_err(|_| "BACKUP: not a local file")?;
    let meta = std::fs::metadata(&path).map_err(|_| "BACKUP: file not found")?;
    if meta.len() as usize > backup::MAX_BACKUP_BYTES {
        return Err("BACKUP: the file is larger than 32 MB".into());
    }
    let bytes = std::fs::read(&path).map_err(|error| format!("BACKUP: {error}"))?;
    let sections = backup::parse_backup(&bytes, hooks(&app).backup_section_names())?;
    let head: Value = serde_json::from_slice(&bytes).unwrap_or(Value::Null);
    Ok(Some(OpenedBackup {
        file: path.file_name().map(|name| name.to_string_lossy().into_owned()).unwrap_or_default(),
        created_at: head.get("createdAt").and_then(Value::as_str).map(str::to_owned),
        app_version: head.get("appVersion").and_then(Value::as_str).map(str::to_owned),
        sections,
    }))
}

/// Applies the sections the owner chose (the shell applies `decks` itself): secret-looking keys
/// are removed first, then the app checks and applies each section
/// ([`crate::app::SiteHooks::backup_apply`]). Returns what was applied and notes for the owner.
#[tauri::command]
pub(crate) async fn backup_apply(webview: Webview, app: AppHandle, sections: Map<String, Value>) -> Result<Value, String> {
    shell_only(&webview)?;
    let mut sections = Value::Object(sections);
    backup::strip_secrets(&mut sections);
    let sections = sections.as_object().cloned().unwrap_or_default();
    hooks(&app).backup_apply(&app, &sections)
}

/// The backup commands ([`crate::commands::BACKUP`]).
pub(crate) fn handler() -> impl Fn(tauri::ipc::Invoke<tauri::Wry>) -> bool + Send + Sync + 'static {
    tauri::generate_handler![backup_collect, backup_export_file, backup_open_file, backup_apply]
}