using System.Collections.Immutable;
using System.Text.Json.Serialization;

namespace StellaOps.Notify.Models;

/// <summary>
/// Quiet hours schedule configuration for suppressing notifications during specified periods.
/// </summary>
public sealed record NotifyQuietHoursSchedule
{
    [JsonConstructor]
    public NotifyQuietHoursSchedule(
        string scheduleId,
        string tenantId,
        string name,
        string cronExpression,
        TimeSpan duration,
        string timeZone,
        string? channelId = null,
        bool enabled = true,
        string? description = null,
        ImmutableDictionary<string, string>? metadata = null,
        string? createdBy = null,
        DateTimeOffset? createdAt = null,
        string? updatedBy = null,
        DateTimeOffset? updatedAt = null)
    {
        ScheduleId = NotifyValidation.EnsureNotNullOrWhiteSpace(scheduleId, nameof(scheduleId));
        TenantId = NotifyValidation.EnsureNotNullOrWhiteSpace(tenantId, nameof(tenantId));
        Name = NotifyValidation.EnsureNotNullOrWhiteSpace(name, nameof(name));
        CronExpression = NotifyValidation.EnsureNotNullOrWhiteSpace(cronExpression, nameof(cronExpression));
        Duration = duration > TimeSpan.Zero ? duration : TimeSpan.FromHours(8);
        TimeZone = NotifyValidation.EnsureNotNullOrWhiteSpace(timeZone, nameof(timeZone));
        ChannelId = NotifyValidation.TrimToNull(channelId);
        Enabled = enabled;
        Description = NotifyValidation.TrimToNull(description);
        Metadata = NotifyValidation.NormalizeStringDictionary(metadata);
        CreatedBy = NotifyValidation.TrimToNull(createdBy);
        CreatedAt = NotifyValidation.EnsureUtc(createdAt ?? DateTimeOffset.UtcNow);
        UpdatedBy = NotifyValidation.TrimToNull(updatedBy);
        UpdatedAt = NotifyValidation.EnsureUtc(updatedAt ?? CreatedAt);
    }

    public static NotifyQuietHoursSchedule Create(
        string scheduleId,
        string tenantId,
        string name,
        string cronExpression,
        TimeSpan duration,
        string timeZone,
        string? channelId = null,
        bool enabled = true,
        string? description = null,
        IEnumerable<KeyValuePair<string, string>>? metadata = null,
        string? createdBy = null,
        DateTimeOffset? createdAt = null,
        string? updatedBy = null,
        DateTimeOffset? updatedAt = null)
    {
        return new NotifyQuietHoursSchedule(
            scheduleId,
            tenantId,
            name,
            cronExpression,
            duration,
            timeZone,
            channelId,
            enabled,
            description,
            ToImmutableDictionary(metadata),
            createdBy,
            createdAt,
            updatedBy,
            updatedAt);
    }

    public string ScheduleId { get; }

    public string TenantId { get; }

    public string Name { get; }

    /// <summary>
    /// Cron expression defining when quiet hours start.
    /// </summary>
    public string CronExpression { get; }

    /// <summary>
    /// Duration of the quiet hours window.
    /// </summary>
    public TimeSpan Duration { get; }

    /// <summary>
    /// IANA time zone for evaluating the cron expression (e.g., "America/New_York").
    /// </summary>
    public string TimeZone { get; }

    /// <summary>
    /// Optional channel ID to scope quiet hours to a specific channel.
    /// If null, applies to all channels.
    /// </summary>
    public string? ChannelId { get; }

    public bool Enabled { get; }

    public string? Description { get; }

    public ImmutableDictionary<string, string> Metadata { get; }

    public string? CreatedBy { get; }

    public DateTimeOffset CreatedAt { get; }

    public string? UpdatedBy { get; }

    public DateTimeOffset UpdatedAt { get; }

    private static ImmutableDictionary<string, string>? ToImmutableDictionary(IEnumerable<KeyValuePair<string, string>>? pairs)
    {
        if (pairs is null)
        {
            return null;
        }

        var builder = ImmutableDictionary.CreateBuilder<string, string>(StringComparer.Ordinal);
        foreach (var (key, value) in pairs)
        {
            builder[key] = value;
        }

        return builder.ToImmutable();
    }
}

/// <summary>
/// Maintenance window for planned suppression of notifications.
/// </summary>
public sealed record NotifyMaintenanceWindow
{
    [JsonConstructor]
    public NotifyMaintenanceWindow(
        string windowId,
        string tenantId,
        string name,
        DateTimeOffset startsAt,
        DateTimeOffset endsAt,
        bool suppressNotifications = true,
        string? reason = null,
        ImmutableArray<string> channelIds = default,
        ImmutableArray<string> ruleIds = default,
        ImmutableDictionary<string, string>? metadata = null,
        string? createdBy = null,
        DateTimeOffset? createdAt = null,
        string? updatedBy = null,
        DateTimeOffset? updatedAt = null)
    {
        WindowId = NotifyValidation.EnsureNotNullOrWhiteSpace(windowId, nameof(windowId));
        TenantId = NotifyValidation.EnsureNotNullOrWhiteSpace(tenantId, nameof(tenantId));
        Name = NotifyValidation.EnsureNotNullOrWhiteSpace(name, nameof(name));
        StartsAt = NotifyValidation.EnsureUtc(startsAt);
        EndsAt = NotifyValidation.EnsureUtc(endsAt);
        SuppressNotifications = suppressNotifications;
        Reason = NotifyValidation.TrimToNull(reason);
        ChannelIds = NormalizeStringArray(channelIds);
        RuleIds = NormalizeStringArray(ruleIds);
        Metadata = NotifyValidation.NormalizeStringDictionary(metadata);
        CreatedBy = NotifyValidation.TrimToNull(createdBy);
        CreatedAt = NotifyValidation.EnsureUtc(createdAt ?? DateTimeOffset.UtcNow);
        UpdatedBy = NotifyValidation.TrimToNull(updatedBy);
        UpdatedAt = NotifyValidation.EnsureUtc(updatedAt ?? CreatedAt);

        if (EndsAt <= StartsAt)
        {
            throw new ArgumentException("EndsAt must be after StartsAt.", nameof(endsAt));
        }
    }

    public static NotifyMaintenanceWindow Create(
        string windowId,
        string tenantId,
        string name,
        DateTimeOffset startsAt,
        DateTimeOffset endsAt,
        bool suppressNotifications = true,
        string? reason = null,
        IEnumerable<string>? channelIds = null,
        IEnumerable<string>? ruleIds = null,
        IEnumerable<KeyValuePair<string, string>>? metadata = null,
        string? createdBy = null,
        DateTimeOffset? createdAt = null,
        string? updatedBy = null,
        DateTimeOffset? updatedAt = null)
    {
        return new NotifyMaintenanceWindow(
            windowId,
            tenantId,
            name,
            startsAt,
            endsAt,
            suppressNotifications,
            reason,
            ToImmutableArray(channelIds),
            ToImmutableArray(ruleIds),
            ToImmutableDictionary(metadata),
            createdBy,
            createdAt,
            updatedBy,
            updatedAt);
    }

    public string WindowId { get; }

    public string TenantId { get; }

    public string Name { get; }

    public DateTimeOffset StartsAt { get; }

    public DateTimeOffset EndsAt { get; }

    /// <summary>
    /// Whether to suppress notifications during the maintenance window.
    /// </summary>
    public bool SuppressNotifications { get; }

    /// <summary>
    /// Reason for the maintenance window.
    /// </summary>
    public string? Reason { get; }

    /// <summary>
    /// Optional list of channel IDs to scope the maintenance window.
    /// If empty, applies to all channels.
    /// </summary>
    public ImmutableArray<string> ChannelIds { get; }

    /// <summary>
    /// Optional list of rule IDs to scope the maintenance window.
    /// If empty, applies to all rules.
    /// </summary>
    public ImmutableArray<string> RuleIds { get; }

    public ImmutableDictionary<string, string> Metadata { get; }

    public string? CreatedBy { get; }

    public DateTimeOffset CreatedAt { get; }

    public string? UpdatedBy { get; }

    public DateTimeOffset UpdatedAt { get; }

    /// <summary>
    /// Checks if the maintenance window is active at the specified time.
    /// </summary>
    public bool IsActiveAt(DateTimeOffset timestamp)
        => SuppressNotifications && timestamp >= StartsAt && timestamp < EndsAt;

    private static ImmutableArray<string> NormalizeStringArray(ImmutableArray<string> values)
    {
        if (values.IsDefaultOrEmpty)
        {
            return ImmutableArray<string>.Empty;
        }

        return values
            .Where(static v => !string.IsNullOrWhiteSpace(v))
            .Select(static v => v.Trim())
            .Distinct(StringComparer.Ordinal)
            .ToImmutableArray();
    }

    private static ImmutableArray<string> ToImmutableArray(IEnumerable<string>? values)
        => values is null ? ImmutableArray<string>.Empty : values.ToImmutableArray();

    private static ImmutableDictionary<string, string>? ToImmutableDictionary(IEnumerable<KeyValuePair<string, string>>? pairs)
    {
        if (pairs is null)
        {
            return null;
        }

        var builder = ImmutableDictionary.CreateBuilder<string, string>(StringComparer.Ordinal);
        foreach (var (key, value) in pairs)
        {
            builder[key] = value;
        }

        return builder.ToImmutable();
    }
}

/// <summary>
/// Operator override for quiet hours or throttle configuration.
/// Allows an operator to temporarily bypass quiet hours or throttling.
/// </summary>
public sealed record NotifyOperatorOverride
{
    [JsonConstructor]
    public NotifyOperatorOverride(
        string overrideId,
        string tenantId,
        NotifyOverrideType overrideType,
        DateTimeOffset expiresAt,
        string? channelId = null,
        string? ruleId = null,
        string? reason = null,
        string? createdBy = null,
        DateTimeOffset? createdAt = null)
    {
        OverrideId = NotifyValidation.EnsureNotNullOrWhiteSpace(overrideId, nameof(overrideId));
        TenantId = NotifyValidation.EnsureNotNullOrWhiteSpace(tenantId, nameof(tenantId));
        OverrideType = overrideType;
        ExpiresAt = NotifyValidation.EnsureUtc(expiresAt);
        ChannelId = NotifyValidation.TrimToNull(channelId);
        RuleId = NotifyValidation.TrimToNull(ruleId);
        Reason = NotifyValidation.TrimToNull(reason);
        CreatedBy = NotifyValidation.TrimToNull(createdBy);
        CreatedAt = NotifyValidation.EnsureUtc(createdAt ?? DateTimeOffset.UtcNow);
    }

    public static NotifyOperatorOverride Create(
        string overrideId,
        string tenantId,
        NotifyOverrideType overrideType,
        DateTimeOffset expiresAt,
        string? channelId = null,
        string? ruleId = null,
        string? reason = null,
        string? createdBy = null,
        DateTimeOffset? createdAt = null)
    {
        return new NotifyOperatorOverride(
            overrideId,
            tenantId,
            overrideType,
            expiresAt,
            channelId,
            ruleId,
            reason,
            createdBy,
            createdAt);
    }

    public string OverrideId { get; }

    public string TenantId { get; }

    public NotifyOverrideType OverrideType { get; }

    public DateTimeOffset ExpiresAt { get; }

    /// <summary>
    /// Optional channel ID to scope the override.
    /// </summary>
    public string? ChannelId { get; }

    /// <summary>
    /// Optional rule ID to scope the override.
    /// </summary>
    public string? RuleId { get; }

    public string? Reason { get; }

    public string? CreatedBy { get; }

    public DateTimeOffset CreatedAt { get; }

    /// <summary>
    /// Checks if the override is active at the specified time.
    /// </summary>
    public bool IsActiveAt(DateTimeOffset timestamp)
        => timestamp < ExpiresAt;
}

/// <summary>
/// Type of operator override.
/// </summary>
[JsonConverter(typeof(JsonStringEnumConverter))]
public enum NotifyOverrideType
{
    /// <summary>
    /// Bypass quiet hours.
    /// </summary>
    BypassQuietHours,

    /// <summary>
    /// Bypass throttling.
    /// </summary>
    BypassThrottle,

    /// <summary>
    /// Bypass maintenance window.
    /// </summary>
    BypassMaintenance,

    /// <summary>
    /// Force suppress notifications.
    /// </summary>
    ForceSuppression
}