using Foxnouns.Backend.Database;
using Foxnouns.Backend.Database.Models;
using Foxnouns.Backend.Middleware;
using Foxnouns.Backend.Services;
using Foxnouns.Backend.Utils;
using Microsoft.AspNetCore.Mvc;
using Microsoft.EntityFrameworkCore;
using Newtonsoft.Json;

namespace Foxnouns.Backend.Controllers.Moderation;

[Route("/api/v2/support")]
public class SupportController(
    ILogger logger,
    DatabaseContext db,
    SupportRendererService supportRenderer,
    ISnowflakeGenerator snowflakeGenerator
) : ApiControllerBase
{
    private readonly ILogger _logger = logger.ForContext<SupportController>();

    [HttpGet]
    [ProducesResponseType<IEnumerable<SupportRendererService.ConversationResponse>>(
        statusCode: StatusCodes.Status200OK
    )]
    [Authorize(":moderator")]
    public async Task<IActionResult> GetOpenConversationsAsync(CancellationToken ct = default)
    {
        var conversations = await db
            .SupportConversations.Where(c => c.Status == SupportConversationStatus.Open)
            .OrderBy(c => c.Id)
            .ToListAsync(ct);

        return Ok(conversations.Select(supportRenderer.ToResponse));
    }

    [HttpGet("{id}")]
    [ProducesResponseType<SupportRendererService.ConversationResponse>(
        statusCode: StatusCodes.Status200OK
    )]
    [Authorize("user.support")]
    public async Task<IActionResult> GetConversationAsync(
        Snowflake id,
        CancellationToken ct = default
    )
    {
        var (_, conversation) = await ResolveConversationAsync(id, ct);

        return Ok(supportRenderer.ToResponse(conversation));
    }

    [HttpGet("{id}/messages")]
    [ProducesResponseType<SupportRendererService.ConversationResponse>(
        statusCode: StatusCodes.Status200OK
    )]
    [Authorize("user.support")]
    public async Task<IActionResult> GetConversationMessagesAsync(
        Snowflake id,
        CancellationToken ct = default
    )
    {
        var (isModerator, conversation) = await ResolveConversationAsync(id, ct);

        var messages = await db
            .SupportMessages.Where(m => m.ConversationId == conversation.Id)
            .OrderBy(m => m.Id)
            .ToListAsync(ct);

        return Ok(messages.Select(m => supportRenderer.ToResponse(m, modView: isModerator)));
    }

    private const int MaxOpenConversations = 5;
    private const int MinTitleLength = 5;
    private const int MaxTitleLength = 512;
    private const int MaxMessageLength = 4096;

    [HttpPost]
    [ProducesResponseType<SupportRendererService.ConversationResponse>(
        statusCode: StatusCodes.Status200OK
    )]
    [Authorize("user.support")]
    public async Task<IActionResult> CreateConversationAsync(
        [FromBody] CreateConversationRequest req
    )
    {
        var openCount = await db
            .SupportConversations.Where(c =>
                c.UserId == CurrentUser!.Id && c.Status == SupportConversationStatus.Open
            )
            .CountAsync();
        if (openCount >= MaxOpenConversations)
            throw new ApiError.BadRequest("Too many open conversations.");

        req.Title.ValidateStringLength("title", MinTitleLength, MaxTitleLength);
        req.InitialMessage.Content?.ValidateStringLength(
            "initial_message.content",
            0,
            MaxMessageLength
        );

        var conversation = new SupportConversation
        {
            Id = snowflakeGenerator.GenerateSnowflake(),
            User = CurrentUser!,
            Title = req.Title,
        };

        var message = new SupportMessage
        {
            Id = snowflakeGenerator.GenerateSnowflake(),
            ConversationId = conversation.Id,
            UserId = CurrentUser!.Id,
            IsAnonymous = false,
            Content = req.InitialMessage.Content,
        };

        db.Add(conversation);
        db.Add(message);

        await db.SaveChangesAsync();

        return Ok(supportRenderer.ToResponse(conversation));
    }

    [HttpPost("{id}/messages")]
    public async Task<IActionResult> CreateMessageAsync(
        Snowflake id,
        [FromBody] CreateMessageRequest req
    )
    {
        var (isModerator, conversation) = await ResolveConversationAsync(id);

        req.Content?.ValidateStringLength("content", 0, MaxMessageLength);
        if (req.IsAnonymous && !isModerator)
        {
            throw new ApiError.BadRequest(
                "Only moderators can mark a message as anonymous.",
                "is_anonymous",
                true
            );
        }

        var message = new SupportMessage
        {
            Id = snowflakeGenerator.GenerateSnowflake(),
            ConversationId = conversation.Id,
            UserId = CurrentUser!.Id,
            IsAnonymous = req.IsAnonymous,
            Content = req.Content,
        };

        db.Add(message);
        await db.SaveChangesAsync();

        return Ok(supportRenderer.ToResponse(message, modView: isModerator));
    }

    private async Task<(
        bool IsModerator,
        SupportConversation Conversation
    )> ResolveConversationAsync(Snowflake id, CancellationToken ct = default)
    {
        var isModerator = CurrentUser!.Role is UserRole.Moderator or UserRole.Admin;

        var conversation = await db.SupportConversations.FindAsync([id], ct);
        if (conversation == null)
            throw new ApiError.NotFound("Conversation not found");
        if (!isModerator && conversation.UserId != CurrentUser.Id)
            throw new ApiError.NotFound("Conversation not found");

        return (isModerator, conversation);
    }

    [HttpPatch("{id}")]
    [ProducesResponseType<SupportRendererService.ConversationResponse>(
        statusCode: StatusCodes.Status200OK
    )]
    [Authorize("user.support")]
    public async Task<IActionResult> UpdateConversationAsync(
        Snowflake id,
        [FromBody] UpdateConversationRequest req
    )
    {
        var isModerator = CurrentUser!.Role is UserRole.Moderator or UserRole.Admin;

        var conversation = await db.SupportConversations.FindAsync(id);
        if (conversation == null)
            throw new ApiError.NotFound("Conversation not found");
        if (!isModerator && conversation.UserId != CurrentUser.Id)
            throw new ApiError.NotFound("Conversation not found");

        if (
            !isModerator
            && (
                req.AssignedTo != null
                || (req.Status != null && req.Status != SupportConversationStatus.Closed)
            )
        )
        {
            throw new ApiError.Forbidden("You can't change those options.");
        }

        if (req.Title != null)
        {
            req.Title.ValidateStringLength("title", MinTitleLength, MaxTitleLength);
            conversation.Title = req.Title;
        }

        if (req.HasProperty(nameof(req.AssignedTo)))
        {
            if (req.AssignedTo == null)
                conversation.AssignedToId = null;
            else
            {
                var assignedToUser = await db.ResolveUserAsync(req.AssignedTo.Value);
                if (assignedToUser.Role is not (UserRole.Admin or UserRole.Moderator))
                {
                    throw new ApiError.BadRequest(
                        "That user is not a moderator.",
                        "assigned_to",
                        req.AssignedTo
                    );
                }

                conversation.AssignedToId = assignedToUser.Id;
            }
        }

        if (req.Status != null)
            conversation.Status = req.Status.Value;

        db.Update(conversation);
        await db.SaveChangesAsync();

        return Ok(supportRenderer.ToResponse(conversation));
    }

    public record CreateConversationRequest(string Title, CreateMessageRequest InitialMessage);

    public record CreateMessageRequest(string? Content, bool IsAnonymous = false);

    public class UpdateConversationRequest : PatchRequest
    {
        public string? Title { get; init; }
        public Snowflake? AssignedTo { get; init; }

        [property: JsonConverter(typeof(ScreamingSnakeCaseEnumConverter))]
        public SupportConversationStatus? Status { get; init; }
    }
}