// Copyright (C) 2026 Danilo M. <danix@danix.xyz>
//
// This program is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License version 2 as
// published by the Free Software Foundation.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.

pragma Singleton

import Quickshell
import Quickshell.Io
import QtQuick
import "Ini.js" as I

// qtmaildir.conf, shared by the four Mail settings pages. qtmaildir reads
// it at startup and never writes it, so editing it under a running
// qtmaildir is safe and applies on its next launch.
//
// The pages edit a draft, never the file: every field writes to it as it is
// typed, and save() writes it out. The draft is shared, so one Save writes
// what all four pages changed, and it survives moving between pages.
Singleton {
    id: root

    readonly property string path: (Quickshell.env("XDG_CONFIG_HOME") || Quickshell.env("HOME") + "/.config")
                                   + "/qtmaildir/qtmaildir.conf"
    // The file as last read or written.
    property string text: ""
    // The file as the draft started from, and the draft.
    property string base: ""
    property string draft: ""
    readonly property bool dirty: root.draft !== root.base
    // Fields holding a value that cannot be written, by section/key; Save
    // waits until there are none.
    property var invalid: ({})
    readonly property bool valid: Object.keys(root.invalid).length === 0
    property string error: ""
    // Whether qtmaildir runs now, so a page can say a change waits for a
    // restart. Rechecked on every refresh().
    property bool running: false

    // The row keys the pages repeat over: account keys, tags, shortcuts.
    // Assigned only when the set changes, never bound to the draft: a new
    // array rebuilds every row of a Repeater, and since every keystroke
    // makes a new draft, a bound model would rebuild the row being typed in
    // and drop its focus after each character. Rows read their values live.
    property var accounts: []
    property var tags: []
    property var shortcuts: []
    function same(a, b) { return JSON.stringify(a) === JSON.stringify(b); }
    onDraftChanged: {
        const acc = I.sections(root.draft).filter(s => s.startsWith("account.")).map(s => s.slice(8));
        const tg = I.entries(root.draft, "tagcolors").map(e => e.key);
        const sc = I.entries(root.draft, "keys").map(e => e.key);
        if (!root.same(acc, root.accounts)) root.accounts = acc;
        if (!root.same(tg, root.tags)) root.tags = tg;
        if (!root.same(sc, root.shortcuts)) root.shortcuts = sc;
    }

    function get(section, key) { return I.get(root.draft, section, key); }
    function entries(section) { return I.entries(root.draft, section); }
    // val null unsets: the line is commented out where it stands.
    function set(section, key, val) { root.draft = I.set(root.draft, section, key, val); }
    function remove(section, key) { root.draft = I.remove(root.draft, section, key); }
    function addAccount(key, pairs) { root.draft = I.addSection(root.draft, "account." + key, pairs); }
    function removeAccount(key) { root.draft = I.removeSection(root.draft, "account." + key); }

    function markInvalid(id, bad) {
        if (!!root.invalid[id] === bad) return;
        const next = Object.assign({}, root.invalid);
        if (bad) next[id] = true; else delete next[id];
        root.invalid = next;
    }

    // Refused when the file changed on disk since the draft began: writing
    // would discard that change unseen. Discard then shows the new file.
    // Never empty, since a header always remains, so FileView.setText is safe
    // here (AGENTS.md: it writes nothing for empty text on an unloaded path).
    function save() {
        if (root.text !== root.base) {
            root.error = "qtmaildir.conf changed on disk since these edits began. Discard to load it, then redo them.";
            return;
        }
        root.error = "";
        root.text = root.draft;
        root.base = root.draft;
        fv.setText(root.draft);
    }

    function discard() {
        root.error = "";
        root.invalid = ({});
        root.base = root.text;
        root.draft = root.text;
    }

    function refresh() {
        fv.reload();
        pg.running = false;
        pg.running = true;
    }

    FileView {
        id: fv
        path: root.path
        atomicWrites: true
        watchChanges: true
        printErrors: false
        // Its own writes come back here too, as the text already held.
        onFileChanged: reload()
        // A clean draft follows the file; a dirty one is kept, and save()
        // notices the file moved under it.
        onLoaded: {
            root.text = text();
            if (!root.dirty) { root.base = root.text; root.draft = root.text; }
        }
        onLoadFailed: if (!root.dirty) { root.text = ""; root.base = ""; root.draft = ""; }
        onSaveFailed: err => root.error = "Cannot write " + root.path + ": " + FileViewError.toString(err)
    }

    Process {
        id: pg
        command: ["pgrep", "-x", "qtmaildir"]
        onExited: code => root.running = code === 0
    }
}