(function (root) {
    'use strict';

    var DEBUG_LOG_KEY = 'debugLogs';
    var DEBUG_LOG_LIMIT = 1200;
    var debugLogsCache = [];
    var earlyDebugLogs = [];
    var debugLogsLoaded = false;
    var debugSaveTimer = null;

    function trimText(value, limit) {
        value = String(value == null ? '' : value);
        limit = Math.max(20, Number(limit || 500));
        return value.length > limit ? value.slice(0, limit) + '…' : value;
    }

    function makePlainLogValue(value, depth) {
        depth = Number(depth || 0);

        if (value == null) return value;
        if (typeof value === 'string') return trimText(value, 900);
        if (typeof value === 'number' || typeof value === 'boolean') return value;
        if (value instanceof Error) return { name: value.name, message: value.message, stack: trimText(value.stack, 1200) };
        if (value instanceof URL) return value.href;
        if (depth > 3) return '[max-depth]';

        if (Array.isArray(value)) {
            return value.slice(0, 40).map(function (item) {
                return makePlainLogValue(item, depth + 1);
            });
        }

        if (typeof value === 'object') {
            var result = {};
            Object.keys(value).slice(0, 60).forEach(function (key) {
                result[key] = makePlainLogValue(value[key], depth + 1);
            });
            return result;
        }

        return trimText(String(value), 300);
    }

    function trimDebugLogs(logs) {
        logs = Array.isArray(logs) ? logs : [];
        return logs.length > DEBUG_LOG_LIMIT ? logs.slice(logs.length - DEBUG_LOG_LIMIT) : logs;
    }

    function scheduleDebugSave() {
        if (!debugLogsLoaded || debugSaveTimer) return;

        debugSaveTimer = root.setTimeout(function () {
            debugSaveTimer = null;
            try {
                var payload = {};
                payload[DEBUG_LOG_KEY] = trimDebugLogs(debugLogsCache);
                chrome.storage.local.set(payload);
            } catch (e) {
                // Diagnostics must never break redirect logic.
            }
        }, 80);
    }

    function initializeDebugLogs() {
        var defaults = {};
        defaults[DEBUG_LOG_KEY] = [];

        try {
            chrome.storage.local.get(defaults, function (items) {
                var stored = Array.isArray(items[DEBUG_LOG_KEY]) ? items[DEBUG_LOG_KEY] : [];
                debugLogsCache = trimDebugLogs(stored.concat(earlyDebugLogs));
                earlyDebugLogs = [];
                debugLogsLoaded = true;
                scheduleDebugSave();
            });
        } catch (e) {
            debugLogsLoaded = true;
        }
    }

    function appendDebugLog(level, event, data) {
        try {
            var entry = {
                time: new Date().toISOString(),
                level: level || 'info',
                event: String(event || 'log'),
                data: makePlainLogValue(data || {})
            };

            if (!debugLogsLoaded) {
                earlyDebugLogs.push(entry);
                earlyDebugLogs = trimDebugLogs(earlyDebugLogs);
                return;
            }

            debugLogsCache.push(entry);
            debugLogsCache = trimDebugLogs(debugLogsCache);
            scheduleDebugSave();
        } catch (e) {
            // Logging must never break redirect logic.
        }
    }

    function log() {
        var args = Array.prototype.slice.call(arguments);
        console.log.apply(console, ['[Auto Mirror Switcher]'].concat(args));
        appendDebugLog('info', args[0] || 'log', { args: args.slice(1) });
    }

    function warn() {
        var args = Array.prototype.slice.call(arguments);
        console.warn.apply(console, ['[Auto Mirror Switcher]'].concat(args));
        appendDebugLog('warn', args[0] || 'warn', { args: args.slice(1) });
    }

    root.AutoMirrorDiagnostics = {
        initializeDebugLogs: initializeDebugLogs,
        appendDebugLog: appendDebugLog,
        log: log,
        warn: warn
    };
})(typeof globalThis !== 'undefined' ? globalThis : this);