<?php

namespace App\Mcp\Support;

use App\Actions\Permissions\PermissionService;
use App\Actions\Tickets\Support\AcceptanceCriteriaChecklistMapper;
use App\Enums\Permission;
use App\Http\Resources\ProjectResource;
use App\Http\Resources\TicketResource;
use App\Models\Project;
use App\Models\Ticket;
use App\Models\TicketStatus;
use App\Models\User;
use Illuminate\Auth\Access\AuthorizationException;
use Illuminate\Auth\AuthenticationException;
use Illuminate\Support\Collection;
use Illuminate\Validation\ValidationException;
use Laravel\Mcp\Request;
use Laravel\Mcp\Response;

class KanbanGitMcp
{
    public function __construct(
        private readonly PermissionService $permissionService,
    ) {}

    /**
     * @throws AuthenticationException
     */
    public function user(Request $request): User
    {
        $user = $request->user();

        if (! $user instanceof User) {
            throw new AuthenticationException('Authentication required.');
        }

        return $user;
    }

    /**
     * @throws AuthorizationException
     */
    public function ensureCanRead(User $user, Project $project): void
    {
        if (! $this->permissionService->allows($user, Permission::ProjectRead, $project)) {
            throw new AuthorizationException('You cannot view this project.');
        }
    }

    /**
     * @throws AuthorizationException
     */
    public function ensureCanWrite(User $user, Project $project): void
    {
        if (! $this->permissionService->allows($user, Permission::ProjectWrite, $project)) {
            throw new AuthorizationException('You cannot update tickets in this project.');
        }
    }

    /**
     * @throws AuthorizationException
     */
    public function ticketForRead(User $user, int $ticketId): Ticket
    {
        $ticket = Ticket::query()
            ->with('project')
            ->find($ticketId);

        if ($ticket === null) {
            throw ValidationException::withMessages([
                'ticket_id' => 'Ticket was not found.',
            ]);
        }

        $this->ensureCanRead($user, $ticket->project);

        return $ticket;
    }

    /**
     * @throws AuthorizationException
     */
    public function ticketForWrite(User $user, int $ticketId): Ticket
    {
        $ticket = Ticket::query()
            ->with('project')
            ->find($ticketId);

        if ($ticket === null) {
            throw ValidationException::withMessages([
                'ticket_id' => 'Ticket was not found.',
            ]);
        }

        $this->ensureCanWrite($user, $ticket->project);

        return $ticket;
    }

    /**
     * @throws AuthorizationException
     */
    public function projectForRead(User $user, ?int $projectId): ?Project
    {
        if ($projectId === null) {
            return null;
        }

        $project = Project::query()->find($projectId);

        if ($project === null) {
            throw ValidationException::withMessages([
                'project_id' => 'Project was not found.',
            ]);
        }

        $this->ensureCanRead($user, $project);

        return $project;
    }

    /**
     * @param  array<string, mixed>  $validated
     * @return Collection<int, TicketStatus>|Response
     */
    public function resolveTicketStatuses(User $user, array $validated, ?Project $project = null): Collection|Response
    {
        $projectIds = $project === null
            ? $this->permissionService->viewableProjectIds($user)
            : [$project->id];

        if ($projectIds === []) {
            return collect();
        }

        $ticketStatusId = $validated['ticket_status_id'] ?? null;
        if ($ticketStatusId !== null) {
            $ticketStatus = TicketStatus::query()
                ->whereIn('project_id', $projectIds)
                ->with('boardColumn')
                ->find((int) $ticketStatusId);

            return $ticketStatus === null
                ? Response::error('Ticket status was not found in a visible project.')
                : collect([$ticketStatus]);
        }

        $query = TicketStatus::query()
            ->whereIn('project_id', $projectIds)
            ->with(['boardColumn', 'project'])
            ->orderBy('project_id')
            ->orderBy('position');

        if (($statusSlug = $validated['status_slug'] ?? null) !== null) {
            $query->where('slug', $statusSlug);
        } elseif (($statusName = $validated['status_name'] ?? null) !== null) {
            $query->where('name', $statusName);
        } else {
            return Response::error('Provide ticket_status_id, status_slug, or status_name.');
        }

        $ticketStatuses = $query->get();

        if ($ticketStatuses->count() <= 1) {
            return $ticketStatuses;
        }

        $matches = $ticketStatuses
            ->map(fn (TicketStatus $ticketStatus): array => [
                'id' => $ticketStatus->id,
                'name' => $ticketStatus->name,
                'project_id' => $ticketStatus->project_id,
                'project_name' => $ticketStatus->project?->name,
                'slug' => $ticketStatus->slug,
            ])
            ->values()
            ->all();

        return Response::error(sprintf(
            'Status lookup is ambiguous. Provide ticket_status_id or project_id. Matches: %s',
            json_encode($matches, JSON_THROW_ON_ERROR | JSON_UNESCAPED_SLASHES),
        ));
    }

    /**
     * @return array<string, mixed>
     */
    public function ticketPayload(Ticket $ticket): array
    {
        $ticket->load([
            'assignee',
            'author',
            'fieldValues.ticketFieldDefinition',
            'fieldValues.userValue',
            'project',
            'ticketPriority',
            'ticketStatus.boardColumn',
            'ticketType',
            'worklogEntries.actor',
        ]);

        return [
            'project' => ProjectResource::make($ticket->project)->resolve(),
            'ticket' => TicketResource::make($ticket)->resolve(),
        ];
    }

    /**
     * @return array{
     *     acceptance_criteria: array<int, array{checked: bool, indent: int, text: string}>,
     *     assignee_user_id: int|null,
     *     author_user_id: int|null,
     *     blocked_comment: string|null,
     *     description: string|null,
     *     is_blocked: bool,
     *     parent_ticket_id: int|null,
     *     story_points: int|null,
     *     ticket_priority_id: int,
     *     ticket_type_id: int,
     *     title: string
     * }
     */
    public function updatePayload(Ticket $ticket): array
    {
        return [
            'acceptance_criteria' => AcceptanceCriteriaChecklistMapper::fromModels(
                $ticket->relationLoaded('acceptanceCriteria')
                    ? $ticket->acceptanceCriteria
                    : $ticket->acceptanceCriteria()->get(),
            ),
            'assignee_user_id' => $ticket->assignee_user_id,
            'author_user_id' => $ticket->author_user_id,
            'blocked_comment' => $ticket->blocked_comment,
            'description' => $ticket->description,
            'is_blocked' => $ticket->is_blocked,
            'parent_ticket_id' => $ticket->parent_ticket_id,
            'story_points' => $ticket->story_points,
            'ticket_priority_id' => $ticket->ticket_priority_id,
            'ticket_type_id' => $ticket->ticket_type_id,
            'title' => $ticket->title,
        ];
    }
}