using System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Net.Http;
using System.Threading;
using HikvisionAttendanceService.Data;

namespace HikvisionAttendanceService;

/// <summary>
/// Resolves sync targets from the attendance_machine repository without site-scope filtering.
/// Source-device selection via <see cref="ResolveRuntimeDevices"/> is unchanged.
/// </summary>
internal sealed partial class HikvisionAttendanceManager
{
    // Prefer universal paths — AccessControl/capabilities returns 404 on many terminals.
    private static readonly string[] TargetIsapiProbePaths =
    {
        "/ISAPI/System/deviceInfo",
        "/ISAPI/AccessControl/UserInfo/capabilities?format=json",
        "/ISAPI/Intelligent/FDLib?format=json",
        "/ISAPI/AccessControl/capabilities?format=json"
    };

    private bool TryResolveSyncTargetByIp(string requestedIp, out HikvisionAttendanceWindowsService.DeviceConfig? device)
    {
        device = null;
        var wantedIp = (requestedIp ?? "").Trim();
        if (wantedIp.Length == 0)
        {
            LogTargetResolve(wantedIp, found: false, machineId: "", port: 0, machineType: "", note: "empty IP");
            return false;
        }

        if (_attendanceMachineRepository == null || !_config.EnableDbIntegration)
        {
            device = ResolveDeviceConfigByIp(wantedIp);
            var found = device != null && !string.IsNullOrWhiteSpace(device.Ip);
            LogTargetResolve(
                wantedIp,
                found,
                device?.DeviceId ?? "",
                device?.Port ?? 0,
                "CONFIG_FALLBACK",
                found ? "resolved from runtime config (DB integration disabled)" : "Target Device Not Found");
            return found;
        }

        if (!_attendanceMachineRepository.TryGetMachineByIp(wantedIp, out var row, out var dbErr))
        {
            LogTargetResolve(wantedIp, found: false, machineId: "", port: 0, machineType: "",
                note: string.IsNullOrWhiteSpace(dbErr) ? "Target Device Not Found" : "Target lookup failed: " + dbErr);
            _logger.Warn("UserSync: Target Device Not Found. TargetMachineIp=\"" + wantedIp + "\".");
            return false;
        }

        if (!IsAttendanceMachineActive(row!))
        {
            LogTargetResolve(
                wantedIp,
                found: false,
                row!.MachineId,
                row.PortNumber,
                row.MachineType,
                "Target device exists but machine_status is not active");
            _logger.Warn("UserSync: target inactive in DB. TargetMachineIp=\"" + wantedIp +
                         "\" machine_id=" + row.MachineId + " machine_status=\"" + row.MachineStatus + "\".");
            return false;
        }

        if (!TryBuildDeviceConfigFromAttendanceMachine(row!, out device, out var buildErr))
        {
            LogTargetResolve(wantedIp, found: false, row!.MachineId, row.PortNumber, row.MachineType, buildErr);
            _logger.Warn("UserSync: target found but could not be built. TargetMachineIp=\"" + wantedIp +
                         "\" reason=\"" + buildErr + "\".");
            return false;
        }

        LogTargetResolve(
            wantedIp,
            found: true,
            device!.DeviceId,
            device.Port,
            row!.MachineType,
            "resolved from attendance_machine");
        return true;
    }

    private bool TryResolveSyncTargetByMachineId(string requestedMachineId, out HikvisionAttendanceWindowsService.DeviceConfig? device)
    {
        device = null;
        var wantedId = (requestedMachineId ?? "").Trim();
        if (wantedId.Length == 0)
        {
            LogTargetResolve("", found: false, machineId: wantedId, port: 0, machineType: "", note: "empty machine_id");
            return false;
        }

        if (_attendanceMachineRepository == null || !_config.EnableDbIntegration)
        {
            device = ResolveDeviceConfig(wantedId);
            var found = device != null && !string.IsNullOrWhiteSpace(device.Ip);
            LogTargetResolve(
                device?.Ip ?? "",
                found,
                wantedId,
                device?.Port ?? 0,
                "CONFIG_FALLBACK",
                found ? "resolved from runtime config (DB integration disabled)" : "Target Device Not Found");
            return found;
        }

        if (!_attendanceMachineRepository.TryGetMachineByMachineId(wantedId, out var row, out var dbErr))
        {
            LogTargetResolve("", found: false, machineId: wantedId, port: 0, machineType: "",
                note: string.IsNullOrWhiteSpace(dbErr) ? "Target Device Not Found" : "Target lookup failed: " + dbErr);
            _logger.Warn("UserSync: Target Device Not Found. TargetDeviceId=\"" + wantedId + "\".");
            return false;
        }

        if (!IsAttendanceMachineActive(row!))
        {
            LogTargetResolve(
                row!.MachineIp,
                found: false,
                row.MachineId,
                row.PortNumber,
                row.MachineType,
                "Target device exists but machine_status is not active");
            _logger.Warn("UserSync: target inactive in DB. TargetDeviceId=\"" + wantedId +
                         "\" machine_status=\"" + row.MachineStatus + "\".");
            return false;
        }

        if (!TryBuildDeviceConfigFromAttendanceMachine(row!, out device, out var buildErr))
        {
            LogTargetResolve(row!.MachineIp, found: false, row.MachineId, row.PortNumber, row.MachineType, buildErr);
            return false;
        }

        LogTargetResolve(device!.Ip, found: true, device.DeviceId, device.Port, row!.MachineType,
            "resolved from attendance_machine");
        return true;
    }

    private bool TryBuildDeviceConfigFromAttendanceMachine(
        AttendanceMachineRow machine,
        out HikvisionAttendanceWindowsService.DeviceConfig? device,
        out string error)
    {
        device = null;
        error = "";
        if (string.IsNullOrWhiteSpace(machine.MachineIp))
        {
            error = "machine_ip empty in attendance_machine";
            return false;
        }

        var configDevices = _config.Devices ?? new List<HikvisionAttendanceWindowsService.DeviceConfig>();
        var credentialFallback = configDevices.FirstOrDefault(d =>
            !string.IsNullOrWhiteSpace(d.Username) && !string.IsNullOrWhiteSpace(d.Password));
        var matchingCfg = configDevices.FirstOrDefault(x =>
            string.Equals((x.Ip ?? "").Trim(), machine.MachineIp.Trim(), StringComparison.OrdinalIgnoreCase));
        var creds = matchingCfg ?? credentialFallback;
        if (creds == null || string.IsNullOrWhiteSpace(creds.Username) || string.IsNullOrWhiteSpace(creds.Password))
        {
            error = "no username/password in serviceconfig Devices for target ip=" + machine.MachineIp;
            return false;
        }

        var deviceId = !string.IsNullOrWhiteSpace(machine.MachineId)
            ? machine.MachineId.Trim()
            : (!string.IsNullOrWhiteSpace(machine.MachineName) ? machine.MachineName.Trim() : machine.MachineIp.Trim());
        var port = machine.PortNumber > 0 ? machine.PortNumber : (creds.Port > 0 ? creds.Port : 8000);

        device = new HikvisionAttendanceWindowsService.DeviceConfig
        {
            DeviceId = deviceId,
            Ip = machine.MachineIp.Trim(),
            Port = port,
            Username = creds.Username,
            Password = creds.Password,
            FingerPrintReaderNo = creds.FingerPrintReaderNo,
            FaceReaderNo = creds.FaceReaderNo,
            GatewayDoorIndex = creds.GatewayDoorIndex,
            Model = string.IsNullOrWhiteSpace(machine.MachineName) ? (creds.Model ?? "") : machine.MachineName,
            SerialNumber = creds.SerialNumber,
            FirmwareVersion = creds.FirmwareVersion,
            SubnetMask = creds.SubnetMask,
            DefaultGateway = creds.DefaultGateway
        };
        return true;
    }

    private static bool IsAttendanceMachineActive(AttendanceMachineRow machine)
    {
        var status = (machine.MachineStatus ?? "").Trim();
        return string.Equals(status, "active", StringComparison.OrdinalIgnoreCase) || status == "1";
    }

    private void LogTargetResolve(string requestedIp, bool found, string machineId, int port, string machineType, string note)
    {
        _logger.Ops("[TARGET_RESOLVE]",
            "requestedIp=" + (requestedIp ?? "") +
            " found=" + (found ? "true" : "false") +
            " machineId=" + (machineId ?? "") +
            " port=" + port +
            " type=" + (machineType ?? "") +
            (string.IsNullOrWhiteSpace(note) ? "" : (" note=\"" + note + "\"")));
    }

    /// <summary>
    /// ISAPI HTTP connectivity probe (Digest) on the HTTP port — not ICMP ping.
    /// Tries several endpoints because firmware/models omit some capabilities URLs (404 is not offline).
    /// </summary>
    private bool TryTestTargetIsapiConnectivity(
        HikvisionAttendanceWindowsService.DeviceConfig device,
        out string outcome,
        out string detail)
    {
        outcome = "";
        detail = "";
        int isapiPort = IsapiPort;
        var ip = (device.Ip ?? "").Trim();
        var requestLabel = "GET ISAPI probe (" + TargetIsapiProbePaths.Length + " paths)";

        var tcpProbe = ConnectivityDiagnostics.ProbeBeforeLogin(ip, isapiPort, tcpTimeoutMs: 5000, tryPing: false);
        if (tcpProbe.TcpChecked && !tcpProbe.TcpOk)
        {
            outcome = "Connection Failed";
            detail = tcpProbe.FriendlyReason;
            LogTargetTest(requestLabel, outcome, detail);
            return false;
        }

        try
        {
            using var handler = BuildDigestHandler(device);
            using var client = new HttpClient(handler) { Timeout = TimeSpan.FromSeconds(15) };

            string lastNonAuthFailure = "";
            var sawHttpResponse = false;

            foreach (var path in TargetIsapiProbePaths)
            {
                var url = "http://" + ip + ":" + isapiPort + path;
                using var response = client.GetAsync(url).GetAwaiter().GetResult();
                sawHttpResponse = true;

                var bodySnippet = "";
                try
                {
                    var body = response.Content.ReadAsStringAsync().GetAwaiter().GetResult();
                    if (!string.IsNullOrWhiteSpace(body))
                        bodySnippet = body.Length > 120 ? body.Substring(0, 120) : body;
                }
                catch
                {
                    // ignore body read errors
                }

                var pathLabel = "GET " + path;
                if (response.StatusCode == HttpStatusCode.Unauthorized ||
                    response.StatusCode == HttpStatusCode.Forbidden)
                {
                    outcome = "Authentication Failed";
                    detail = pathLabel + " → HTTP " + (int)response.StatusCode + " " + response.ReasonPhrase;
                    LogTargetTest(pathLabel, outcome, detail);
                    return false;
                }

                if (response.IsSuccessStatusCode)
                {
                    outcome = "OK";
                    detail = pathLabel + " → HTTP " + (int)response.StatusCode;
                    LogTargetTest(pathLabel, outcome, detail);
                    return true;
                }

                lastNonAuthFailure = pathLabel + " → HTTP " + (int)response.StatusCode + " " + response.ReasonPhrase +
                                     (string.IsNullOrWhiteSpace(bodySnippet) ? "" : (" body=\"" + bodySnippet + "\""));
                LogTargetTest(pathLabel, "probe_miss", lastNonAuthFailure);
            }

            // Device answered HTTP but probe URLs are unsupported on this firmware.
            // Allow sync to proceed; real UserInfo / FaceDataRecord calls will report real errors.
            if (sawHttpResponse)
            {
                outcome = "OK";
                detail = "device reachable on HTTP " + isapiPort +
                         "; probe URLs unsupported (last: " + lastNonAuthFailure + ")";
                LogTargetTest(requestLabel, outcome, detail);
                return true;
            }

            outcome = "Connection Failed";
            detail = string.IsNullOrWhiteSpace(lastNonAuthFailure)
                ? "No HTTP response from ISAPI probes."
                : lastNonAuthFailure;
            LogTargetTest(requestLabel, outcome, detail);
            return false;
        }
        catch (TaskCanceledException ex)
        {
            outcome = "Connection Failed";
            detail = "ISAPI request timed out: " + ex.Message;
            LogTargetTest(requestLabel, outcome, detail);
            return false;
        }
        catch (HttpRequestException ex)
        {
            outcome = "Connection Failed";
            detail = ex.Message;
            LogTargetTest(requestLabel, outcome, detail);
            return false;
        }
        catch (Exception ex)
        {
            outcome = "Connection Failed";
            detail = ex.GetType().Name + ": " + ex.Message;
            LogTargetTest(requestLabel, outcome, detail);
            return false;
        }
    }

    private void LogTargetTest(string request, string outcome, string detail)
    {
        _logger.Ops("[TARGET_TEST]",
            "request=" + request +
            " outcome=" + outcome +
            (string.IsNullOrWhiteSpace(detail) ? "" : (" detail=\"" + detail + "\"")));
    }

    private void LogDbToDeviceResult(
        string employeeNo,
        string createUser,
        string faceUpload,
        string verification,
        string finalResult)
    {
        _logger.Ops("[DB_TO_DEVICE]",
            "employee=" + employeeNo +
            " createUser=" + createUser +
            " faceUpload=" + faceUpload +
            " verification=" + verification +
            " finalResult=" + finalResult);
    }

    /// <summary>
    /// Resolves configured sync targets from DB (no scope filter), tests ISAPI connectivity, returns ready targets.
    /// </summary>
    private List<HikvisionAttendanceWindowsService.DeviceConfig> CollectTestedSyncTargets(
        HikvisionAttendanceWindowsService.DeviceConfig? source,
        bool hasSource,
        CancellationToken ct)
    {
        var targets = new List<HikvisionAttendanceWindowsService.DeviceConfig>();
        foreach (var targetIp in _config.TargetMachineIps ?? Enumerable.Empty<string>())
        {
            ct.ThrowIfCancellationRequested();
            if (!TryResolveSyncTargetByIp(targetIp, out var device) || device == null)
                continue;

            if (targets.Any(x => string.Equals(x.Ip, device.Ip, StringComparison.OrdinalIgnoreCase)))
                continue;

            if (hasSource &&
                string.Equals((device.Ip ?? "").Trim(), (source!.Ip ?? "").Trim(), StringComparison.OrdinalIgnoreCase) &&
                !_config.EnableTemplateDbToDeviceSync)
            {
                _logger.Diag("user_sync",
                    "target skipped — same as source IP and DB->device restore disabled. TargetMachineIp=\"" + targetIp + "\".");
                continue;
            }

            if (!TryTestTargetIsapiConnectivity(device, out var testOutcome, out var testDetail))
            {
                _logger.Warn("UserSync: target connectivity failed. TargetMachineIp=\"" + targetIp +
                             "\" machine_id=" + device.DeviceId + " outcome=\"" + testOutcome +
                             "\" detail=\"" + testDetail + "\".");
                var failTitle = testOutcome == "Authentication Failed"
                    ? "Authentication Failed."
                    : "Connection Failed.";
                var failLines = new[]
                {
                    "MACHINE " + (device.DeviceId ?? ""),
                    "",
                    failTitle,
                    "",
                    "Machine IP : " + (device.Ip ?? ""),
                    "ISAPI HTTP Port : " + IsapiPort,
                    "Detail : " + (string.IsNullOrWhiteSpace(testDetail) ? "(none)" : testDetail),
                    ""
                };
                _logger.Biz(BizChannel.UserSync, failLines);
                _logger.BizSeparator(BizChannel.UserSync);
                if (_config.EnableInitialDepartmentSync)
                {
                    _logger.Biz(BizChannel.DepartmentalSync, failLines);
                    _logger.BizSeparator(BizChannel.DepartmentalSync);
                }
                if (_config.EnableTemplateDbToDeviceSync)
                {
                    _logger.Biz(BizChannel.Template,
                        "Target Device :",
                        "",
                        (device.Ip ?? ""),
                        "",
                        failTitle,
                        "",
                        "Detail : " + (string.IsNullOrWhiteSpace(testDetail) ? "(none)" : testDetail),
                        "");
                    _logger.BizSeparator(BizChannel.Template);
                }

                continue;
            }

            targets.Add(device);
        }

        foreach (var tid in _config.TargetDeviceIds ?? Enumerable.Empty<string>())
        {
            ct.ThrowIfCancellationRequested();
            if (!TryResolveSyncTargetByMachineId(tid, out var device) || device == null)
                continue;

            if (targets.Any(x =>
                    string.Equals(x.Ip, device.Ip, StringComparison.OrdinalIgnoreCase) ||
                    DeviceIdentity.CanonicalLookupKey(x.DeviceId) == DeviceIdentity.CanonicalLookupKey(device.DeviceId)))
                continue;

            if (hasSource &&
                DeviceIdentity.CanonicalLookupKey(device.DeviceId) == DeviceIdentity.CanonicalLookupKey(source!.DeviceId))
            {
                if (!_config.EnableTemplateDbToDeviceSync)
                {
                    _logger.Warn("UserSync: target skipped — same as source. deviceId=\"" + device.DeviceId + "\".");
                    continue;
                }
            }

            if (!TryTestTargetIsapiConnectivity(device, out var testOutcome, out var testDetail))
            {
                _logger.Warn("UserSync: target connectivity failed. TargetDeviceId=\"" + tid +
                             "\" machine_id=" + device.DeviceId + " outcome=\"" + testOutcome +
                             "\" detail=\"" + testDetail + "\".");
                continue;
            }

            targets.Add(device);
        }

        return targets;
    }
}