// Author:  cirakg & claude ai
// Summary: Runs an import as a resumable job: detect the format, parse, replace old imports, find duplicates, store entry by entry.
//
// README 11. Phases, each done in small steps (one timer event each):
//   PARSE    otpauth URIs (one per step) or Aegis JSON (Json/Aegis token
//            steps). Incomplete JSON is kept in the ImportBuffer and the
//            import ends with "waiting for more".
//   REPLACE  in Replace mode, delete earlier imported entries (locked ones
//            only while unlocked; others are kept and reported).
//   INDEX    read every header once (a few per step) into a fingerprint
//            index (duplicates) and a name index (possible replacements).
//   STORE    one item per step: skip, report, or add to the vault. A crash
//            leaves only whole entries.
// The report is complete when step() returns true.
//
// Memory: while JSON is parsed the pasted text is held once, as the
// tokenizer's bytes, and parsed items are kept packed (ImportItem.pack);
// the M8 numbers are in docs/PERFORMANCE.md.

import Toybox.Lang;

class Importer extends Jobs.Job {

    static const MODE_APPEND = 0;
    static const MODE_REPLACE = 1;
    static const MODE_CANCEL = 2;

    static const P_PARSE = 0;
    static const P_REPLACE = 1;
    static const P_INDEX = 2;
    static const P_STORE = 3;
    static const P_DONE = 4;

    static const HEADERS_PER_STEP = 4;
    static const URIS_PER_STEP = 1;

    var report as ImportReport = new ImportReport();
    var phase as Number = P_PARSE;

    private var _vault as Vault;
    private var _mode as Number;
    private var _locked as Boolean;
    private var _now as Long;
    private var _text as String = "";
    private var _uris as Array<String>? = null;
    private var _aegis as AegisReader? = null;
    private var _items as Array<ByteArray> = [] as Array<ByteArray>;
    private var _groups as Dictionary<String, String> = {} as Dictionary<String, String>;
    private var _cursor as Number = 0;
    private var _ids as Array<String> = [] as Array<String>;
    private var _fingerprints as Dictionary<String, String> = {} as Dictionary<String, String>;
    private var _names as Dictionary<String, String> = {} as Dictionary<String, String>;
    // How items are named in messages: "URI 3" or "entry 7 'GitHub'".
    private var _kind as String = "entry";

    // text: the joined import fields. A waiting earlier part is prepended.
    function initialize(vault as Vault, text as String, mode as Number, locked as Boolean, now as Long) {
        Job.initialize();
        _vault = vault;
        _mode = mode;
        _locked = locked;
        _now = now;
        var keys = vault.keyManager.deviceKeys();
        var earlier = ImportBuffer.load(vault.storage(), keys, now);
        _text = earlier.length() > 0 ? earlier + text : text;
        detect();
    }

    // Progress for the UI, 0-100.
    function percent() as Number {
        if (phase == P_PARSE) {
            var a = _aegis;
            if (a != null) {
                return 40 * a.position() / (a.size() > 0 ? a.size() : 1);
            }
            var u = _uris;
            return u != null && u.size() > 0 ? 40 * _cursor / u.size() : 0;
        }
        if (phase == P_STORE) {
            return _items.size() > 0 ? 50 + 50 * _cursor / _items.size() : 100;
        }
        return phase == P_DONE ? 100 : 45;
    }

    private function detect() as Void {
        var trimmed = Text.trim(_text);
        if (trimmed.length() == 0) {
            finishWith("the import fields are empty");
            return;
        }
        if (trimmed.find("{") == 0) {
            // The untrimmed text: an incomplete part is saved exactly as
            // received (a cut can fall on a space inside a string).
            _aegis = new AegisReader(Bytes.fromUtf8(_text));
            _text = "";
            return;
        }
        if (Text.findIgnoreCase(trimmed, OtpAuth.MIGRATION_PREFIX, 0) >= 0) {
            finishWith("Google Authenticator exports are not supported yet. Export from Aegis, or paste otpauth:// links");
            return;
        }
        var first = Text.findIgnoreCase(trimmed, OtpAuth.PREFIX, 0);
        if (first < 0) {
            finishWith("not recognised. Paste otpauth:// links or an unencrypted Aegis JSON export");
            return;
        }
        if (first > 0) {
            report.addDetail("Ignored " + first + " characters before the first otpauth:// link");
        }
        _uris = OtpAuth.splitUris(trimmed);
        _kind = "URI";
        _text = "";
    }

    private function finishWith(failure as String) as Void {
        report.failure = failure;
        ImportBuffer.clear(_vault.storage());
        phase = P_DONE;
    }

    function step(budget as Number) as Boolean {
        Diag.sampleMemory();
        if (phase == P_PARSE) {
            parseStep();
        } else if (phase == P_REPLACE) {
            replaceStep();
        } else if (phase == P_INDEX) {
            indexStep();
        } else if (phase == P_STORE) {
            storeStep();
        }
        return phase == P_DONE;
    }

    private function parseStep() as Void {
        var aegis = _aegis;
        if (aegis != null) {
            var status = aegis.step();
            if (status == AegisReader.RUNNING) {
                return;
            }
            if (status == AegisReader.INCOMPLETE) {
                var data = aegis.data();
                _aegis = null;
                if (ImportBuffer.save(_vault.storage(), _vault.keyManager.deviceKeys(), data, _now)) {
                    var text = Bytes.toUtf8(data);
                    report.waitingChars = text != null ? text.length() : data.size();
                    phase = P_DONE;
                } else {
                    finishWith("the JSON is incomplete and too long to wait for more (" + data.size() + " bytes, at most "
                        + ImportBuffer.MAX_TEXT_BYTES + ")");
                }
                return;
            }
            if (status == AegisReader.FAILED) {
                _aegis = null;
                finishWith(aegis.error as String);
                return;
            }
            _items = aegis.items;
            _groups = aegis.groups;
            _aegis = null;
            startReplace();
            return;
        }
        var uris = _uris as Array<String>;
        for (var n = 0; n < URIS_PER_STEP && _cursor < uris.size(); n++) {
            _items.add(OtpAuth.parse(uris[_cursor], _cursor + 1).pack());
            _cursor++;
        }
        if (_cursor >= uris.size()) {
            _uris = null;
            startReplace();
        }
    }

    private function startReplace() as Void {
        ImportBuffer.clear(_vault.storage());
        _ids = _vault.ids();
        _ids.addAll(_vault.pendingIds());
        _cursor = 0;
        phase = _mode == MODE_REPLACE ? P_REPLACE : P_INDEX;
    }

    // Replace mode: delete one earlier imported entry per step.
    private function replaceStep() as Void {
        var kept = 0;
        while (_cursor < _ids.size()) {
            var id = _ids[_cursor];
            _cursor++;
            var header = _vault.anyHeader(id);
            if (header == null || header.source != Entry.SOURCE_IMPORT) {
                continue;
            }
            if (_vault.pendingIds().indexOf(id) >= 0 || (header.locked && !_vault.session.isUnlocked())) {
                kept++;
                report.addDetail("Kept locked imported entry " + id + ": unlock first to replace it");
                continue;
            }
            try {
                _vault.remove(id);
                report.removed++;
            } catch (e instanceof VaultError) {
                report.addDetail("Could not remove " + id);
            }
            return; // one deletion per step
        }
        _ids = _vault.ids();
        _ids.addAll(_vault.pendingIds());
        _cursor = 0;
        phase = P_INDEX;
    }

    // Read a few headers into the duplicate indexes.
    private function indexStep() as Void {
        for (var n = 0; n < HEADERS_PER_STEP && _cursor < _ids.size(); n++) {
            var id = _ids[_cursor];
            _cursor++;
            var header = _vault.anyHeader(id);
            if (header != null) {
                remember(header, id);
            }
        }
        if (_cursor >= _ids.size()) {
            _cursor = 0;
            phase = P_STORE;
        }
    }

    private function remember(header as Entry, id as String) as Void {
        var fp = header.fingerprint;
        if (fp != null) {
            _fingerprints[Bytes.toHex(fp)] = id;
        }
        if (header.kind == Entry.KIND_OTP && (header.name.length() > 0 || header.account.length() > 0)) {
            _names[nameKey(header)] = id;
        }
    }

    private function nameKey(e as Entry) as String {
        return e.name.toLower() + "\n" + e.account.toLower();
    }

    // Store (or report) one item.
    private function storeStep() as Void {
        if (_cursor >= _items.size()) {
            phase = P_DONE;
            return;
        }
        var packed = _items[_cursor];
        _items[_cursor] = []b;
        var item = ImportItem.unpack(packed, _groups);
        Bytes.wipe(packed); // the parsed secret; about 110 bytes
        _cursor++;
        var kind = _kind;
        var note = item.note;
        if (note != null) {
            report.addDetail(item.describe(kind) + ": " + note);
        }
        var skipped = item.skipped;
        if (skipped != null) {
            report.skipped++;
            report.addDetail(item.describe(kind) + ": skipped, " + skipped);
            return;
        }
        var problem = item.problem;
        var e = item.entry;
        if (problem != null || e == null) {
            report.errors++;
            report.addDetail(item.describe(kind) + ": " + (problem != null ? problem : "invalid"));
            return;
        }
        var fp = Bytes.toHex(_vault.keyManager.fingerprint(e));
        var existing = _fingerprints[fp];
        if (existing != null) {
            report.duplicates++;
            report.addDetail(item.describe(kind) + ": duplicate of " + existing);
            e.wipeSecrets();
            return;
        }
        var sameName = _names[nameKey(e)];
        e.locked = _locked;
        e.created = _now;
        try {
            var id = _vault.add(e);
            report.imported++;
            if (_vault.pendingIds().indexOf(id) >= 0) {
                report.pendingLocked++;
            }
            if (sameName != null) {
                report.addDetail(item.describe(kind) + ": added as " + id + ", possible replacement for " + sameName
                    + ". Delete the old one with Manage entry");
            }
            remember(e, id);
        } catch (err instanceof VaultError) {
            report.errors++;
            report.addDetail(item.describe(kind) + ": not stored (" + err.getErrorMessage() + ")");
            if (err.code == VaultError.FULL || err.code == VaultError.LIMIT) {
                report.addDetail("Stopped: " + (_items.size() - _cursor) + " more entries not imported");
                report.errors += _items.size() - _cursor;
                phase = P_DONE;
            }
        }
        e.wipeSecrets();
    }
}