using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Xml.Linq;

namespace HanvonF710XAttendanceService
{
    internal sealed class DeviceSettingsConfig
    {
        public string Mode { get; private set; }
        public int? SiteId { get; private set; }
        public List<DeviceRule> Devices { get; } = new List<DeviceRule>();
        public TemplateTransferConfig TemplateTransfer { get; private set; }

        public static bool TryLoad(string path, out DeviceSettingsConfig config, out string error)
        {
            config = null;
            error = null;

            try
            {
                if (string.IsNullOrWhiteSpace(path))
                {
                    error = "Device settings path is empty.";
                    return false;
                }

                if (!File.Exists(path))
                {
                    config = new DeviceSettingsConfig();
                    return true;
                }

                var doc = XDocument.Load(path);
                var root = doc.Root;
                if (root == null || !string.Equals(root.Name.LocalName, "DeviceSettings", StringComparison.OrdinalIgnoreCase))
                {
                    error = $"Invalid device settings root element. Expected <DeviceSettings>, found <{root?.Name.LocalName ?? "null"}>.";
                    return false;
                }

                var parsed = new DeviceSettingsConfig
                {
                    Mode = (string)root.Attribute("Mode")
                };

                var rootSiteIdStr = (string)root.Attribute("SiteId") ?? (string)root.Attribute("SITE_ID") ?? (string)root.Attribute("SiteID");
                if (!string.IsNullOrWhiteSpace(rootSiteIdStr) && int.TryParse(rootSiteIdStr.Trim(), out var rootSiteId))
                {
                    parsed.SiteId = rootSiteId;
                }

                foreach (var deviceEl in root.Elements().Where(e => string.Equals(e.Name.LocalName, "Device", StringComparison.OrdinalIgnoreCase)))
                {
                    var ip = (string)deviceEl.Attribute("IpAddress") ?? (string)deviceEl.Attribute("Ip") ?? "";
                    var enabledStr = (string)deviceEl.Attribute("Enabled");
                    if (string.IsNullOrWhiteSpace(ip) || string.IsNullOrWhiteSpace(enabledStr))
                    {
                        continue;
                    }

                    if (!TryParseBool(enabledStr, out var enabled))
                    {
                        continue;
                    }

                    int? siteId = null;
                    var siteIdStr = (string)deviceEl.Attribute("SiteId") ?? (string)deviceEl.Attribute("SITE_ID") ?? (string)deviceEl.Attribute("SiteID");
                    if (!string.IsNullOrWhiteSpace(siteIdStr) && int.TryParse(siteIdStr.Trim(), out var parsedSiteId))
                    {
                        siteId = parsedSiteId;
                    }

                    parsed.Devices.Add(new DeviceRule(ip.Trim(), enabled, siteId));
                }

                // If SiteId is not specified at root, but devices specify a single consistent SiteId, use it.
                if (!parsed.SiteId.HasValue)
                {
                    var distinct = parsed.Devices.Where(d => d.SiteId.HasValue).Select(d => d.SiteId.Value).Distinct().ToList();
                    if (distinct.Count == 1)
                    {
                        parsed.SiteId = distinct[0];
                    }
                }

                var templateTransferEl = root.Elements().FirstOrDefault(e => string.Equals(e.Name.LocalName, "TemplateTransfer", StringComparison.OrdinalIgnoreCase));
                if (templateTransferEl != null)
                {
                    var ttEnabled = TryParseBool((string)templateTransferEl.Attribute("Enabled"), out var tt) && tt;
                    var ttConfig = new TemplateTransferConfig(ttEnabled);

                    foreach (var jobEl in templateTransferEl.Elements().Where(e => string.Equals(e.Name.LocalName, "Job", StringComparison.OrdinalIgnoreCase)))
                    {
                        var id = (string)jobEl.Attribute("Id") ?? "";
                        var enabled = TryParseBool((string)jobEl.Attribute("Enabled"), out var jEnabled) && jEnabled;
                        var sourceIp = (string)jobEl.Attribute("SourceIp") ?? (string)jobEl.Attribute("SourceIP") ?? "";

                        if (string.IsNullOrWhiteSpace(id))
                        {
                            continue;
                        }

                        var targets = new List<string>();
                        foreach (var targetEl in jobEl.Elements().Where(e => string.Equals(e.Name.LocalName, "Target", StringComparison.OrdinalIgnoreCase)))
                        {
                            var tip = (string)targetEl.Attribute("Ip") ?? (string)targetEl.Attribute("IpAddress") ?? "";
                            if (!string.IsNullOrWhiteSpace(tip))
                            {
                                targets.Add(tip.Trim());
                            }
                        }

                        // Optional comma-separated list of employee IDs for DB_TO_DEVICE filtering
                        var empIdsAttr = (string)jobEl.Attribute("EmpIds") ?? (string)jobEl.Attribute("EmpIDs");
                        List<string> empIds = null;
                        if (!string.IsNullOrWhiteSpace(empIdsAttr))
                        {
                            empIds = empIdsAttr
                                .Split(new[] { ',' }, StringSplitOptions.RemoveEmptyEntries)
                                .Select(v => v.Trim())
                                .Where(v => v.Length > 0)
                                .ToList();
                        }

                        var departmentIdsAttr = (string)jobEl.Attribute("DepartmentIds")
                            ?? (string)jobEl.Attribute("DepartmentIDs")
                            ?? (string)jobEl.Attribute("DeptIds");
                        List<string> departmentIds = null;
                        if (!string.IsNullOrWhiteSpace(departmentIdsAttr))
                        {
                            departmentIds = departmentIdsAttr
                                .Split(new[] { ',' }, StringSplitOptions.RemoveEmptyEntries)
                                .Select(v => v.Trim())
                                .Where(v => v.Length > 0)
                                .ToList();
                        }

                        ttConfig.Jobs.Add(new TemplateTransferJob(id.Trim(), enabled, sourceIp.Trim(), targets, empIds, departmentIds));
                    }

                    parsed.TemplateTransfer = ttConfig;
                }

                config = parsed;
                return true;
            }
            catch (Exception ex)
            {
                error = $"Failed to load device settings: {ex.Message}";
                return false;
            }
        }

        public bool HasAnyAllowlistedDeviceIp()
            => Devices.Any(d => d.Enabled);

        public HashSet<string> GetAllowlistedIps()
            => new HashSet<string>(Devices.Where(d => d.Enabled).Select(d => d.IpAddress), StringComparer.OrdinalIgnoreCase);

        public HashSet<string> GetBlocklistedIps()
            => new HashSet<string>(Devices.Where(d => !d.Enabled).Select(d => d.IpAddress), StringComparer.OrdinalIgnoreCase);

        private static bool TryParseBool(string value, out bool result)
        {
            if (string.IsNullOrWhiteSpace(value))
            {
                result = false;
                return false;
            }

            return bool.TryParse(value.Trim(), out result);
        }
    }

    internal sealed class DeviceRule
    {
        public DeviceRule(string ipAddress, bool enabled, int? siteId)
        {
            IpAddress = ipAddress ?? "";
            Enabled = enabled;
            SiteId = siteId;
        }

        public string IpAddress { get; }
        public bool Enabled { get; }
        public int? SiteId { get; }
    }

    internal sealed class TemplateTransferConfig
    {
        public TemplateTransferConfig(bool enabled)
        {
            Enabled = enabled;
        }

        public bool Enabled { get; }
        public List<TemplateTransferJob> Jobs { get; } = new List<TemplateTransferJob>();
    }

    internal sealed class TemplateTransferJob
    {
        public TemplateTransferJob(string id, bool enabled, string sourceIp, List<string> targetIps, List<string> empIds, List<string> departmentIds = null)
        {
            Id = id ?? "";
            Enabled = enabled;
            SourceIp = sourceIp ?? "";
            TargetIps = targetIps ?? new List<string>();
            EmpIds = empIds ?? new List<string>();
            DepartmentIds = departmentIds ?? new List<string>();
        }

        public string Id { get; }
        public bool Enabled { get; }
        public string SourceIp { get; }
        public List<string> TargetIps { get; }
        public List<string> EmpIds { get; }
        public List<string> DepartmentIds { get; }
    }
}