using System.Text.Json;
using Fleet.Core;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Routing;
using Monitor.Backend.Application;
using Monitor.Protocol;

namespace Monitor.Backend.Api;

/// <summary>API 令牌、站点设置与保留期、用户。令牌明文只在创建的响应里出现一次。</summary>
public static class SystemEndpoints
{
    private const string TokensTag = "admin-api-tokens";
    private const string SettingsTag = "admin-settings";
    private const string UsersTag = "admin-users";

    public static void Map(RouteGroupBuilder group)
    {
        group.MapGet("/api-tokens", ListTokensAsync)
            .Api("api_tokens_list", "API tokens", TokensTag).Returns<PageDto<ApiTokenDto>>().ProducesProblems(401, 403);
        group.MapPost("/api-tokens", CreateTokenAsync)
            .Api("api_tokens_create", "Create an API token (scope read or admin); the plaintext is returned only once", TokensTag)
            .Returns<CreatedApiTokenDto>(StatusCodes.Status201Created).ProducesProblems(400, 401, 403);
        group.MapDelete("/api-tokens/{id}", RevokeTokenAsync)
            .Api("api_tokens_revoke", "Revoke an API token", TokensTag).Returns<object>(StatusCodes.Status204NoContent).ProducesProblems(401, 403);

        group.MapGet("/settings", ListSettingsAsync)
            .Api("settings_list", "Site settings and retention periods", SettingsTag).Returns<PageDto<SettingDto>>().ProducesProblems(401, 403);
        group.MapPatch("/settings", PatchSettingsAsync)
            .Accepts<Dictionary<string, JsonElement>>("application/merge-patch+json", "application/json")
            .Api("settings_update", "Change settings (merge-patch)", SettingsTag).Returns<PageDto<SettingDto>>().ProducesProblems(400, 401, 403);

        group.MapGet("/users", ListUsersAsync)
            .Api("users_list", "Panel users", UsersTag).Returns<PageDto<UserDto>>().ProducesProblems(401, 403);
        group.MapPost("/users", CreateUserAsync)
            .Api("users_create", "Create a panel user", UsersTag).Returns<UserDto>(StatusCodes.Status201Created).ProducesProblems(400, 401, 403, 409);
        group.MapPatch("/users/{id}", ChangePasswordAsync)
            .Api("users_update", "Change a user's password", UsersTag).Returns<object>(StatusCodes.Status204NoContent).ProducesProblems(400, 401, 403);
    }

    private static async Task<IResult> ListTokensAsync(AuthService auth, CancellationToken ct) =>
        TypedResults.Json(new PageDto<ApiTokenDto>([.. (await auth.ListApiTokensAsync(ct)).Select(Mappers.ToDto)], null), ApiJsonContext.Default.PageDtoApiTokenDto);

    private static async Task<IResult> CreateTokenAsync(HttpContext http, AuthService auth, CreateApiTokenRequest request)
    {
        Result<CreatedApiToken> result = await auth.CreateApiTokenAsync(request.Name ?? "", request.Scope ?? "", http.RequestAborted);
        if (!result.TryGet(out CreatedApiToken? created, out FleetError? error))
        {
            return Problems.From(http, error);
        }

        http.Response.Headers.CacheControl = "no-store";
        return TypedResults.Json(new CreatedApiTokenDto(Mappers.ToDto(created.Record), created.Plaintext), ApiJsonContext.Default.CreatedApiTokenDto, statusCode: StatusCodes.Status201Created);
    }

    private static async Task<IResult> RevokeTokenAsync(AuthService auth, string id, CancellationToken ct)
    {
        await auth.RevokeApiTokenAsync(id, ct);
        return TypedResults.NoContent();
    }

    private static async Task<IResult> ListSettingsAsync(SettingsService settings, CancellationToken ct) =>
        TypedResults.Json(new PageDto<SettingDto>([.. (await settings.ListAsync(ct)).Select(Mappers.ToDto)], null), ApiJsonContext.Default.PageDtoSettingDto);

    private static async Task<IResult> PatchSettingsAsync(HttpContext http, SettingsService settings, AgentService agents, Dictionary<string, JsonElement> changes)
    {
        Result<IReadOnlyList<SettingView>> result = await settings.PatchAsync(changes, http.RequestAborted);
        if (result.IsSuccess && changes.ContainsKey(SettingsService.AutoLink))
        {
            await agents.AfterAgentSetChangedAsync(http.RequestAborted); // 自动连接开关变了：重新下发各 Probe 的 Agent 列表和各 Agent 允许的 Probe
        }

        return result.TryGet(out IReadOnlyList<SettingView>? views, out FleetError? error)
            ? TypedResults.Json(new PageDto<SettingDto>([.. views.Select(Mappers.ToDto)], null), ApiJsonContext.Default.PageDtoSettingDto)
            : Problems.From(http, error);
    }

    private static async Task<IResult> ListUsersAsync(AuthService auth, CancellationToken ct) =>
        TypedResults.Json(new PageDto<UserDto>([.. (await auth.ListUsersAsync(ct)).Select(Mappers.ToDto)], null), ApiJsonContext.Default.PageDtoUserDto);

    private static async Task<IResult> CreateUserAsync(HttpContext http, AuthService auth, CreateUserRequest request)
    {
        Result<UserRecord> result = await auth.CreateUserAsync(request.Username ?? "", request.Password ?? "", http.RequestAborted);
        if (!result.TryGet(out UserRecord? user, out FleetError? error))
        {
            return Problems.From(http, error);
        }

        http.Response.Headers.Location = "/api/admin/users";
        return TypedResults.Json(Mappers.ToDto(user), ApiJsonContext.Default.UserDto, statusCode: StatusCodes.Status201Created);
    }

    private static async Task<IResult> ChangePasswordAsync(HttpContext http, AuthService auth, ChangePasswordRequest request, string id)
    {
        Result<bool> result = await auth.ChangePasswordAsync(id, request.Password ?? "", http.RequestAborted);
        return result.IsSuccess ? TypedResults.NoContent() : Problems.From(http, result.Error);
    }
}