<?php

namespace App\Services;

use Illuminate\Support\Facades\DB;
use Illuminate\Support\Str;
use RuntimeException;
use Throwable;

class ProjectSearchChatService
{
    private const SESSION_KEY = 'project_search_chat_session_uuid';

    public function isAvailable(): bool
    {
        try {
            return DB::connection('project_search')->getSchemaBuilder()->hasTable('project_search_chat_sessions');
        } catch (Throwable) {
            return false;
        }
    }

    /**
     * @return array<string, mixed>|null
     */
    public function activeSession(string $username): ?array
    {
        $uuid = session(self::SESSION_KEY);
        if (! is_string($uuid) || $uuid === '') {
            return null;
        }

        $row = DB::connection('project_search')
            ->table('project_search_chat_sessions')
            ->where('session_uuid', $uuid)
            ->where('username', $username)
            ->where('status', 'active')
            ->first();

        return $row ? $this->mapSession($row) : null;
    }

    /**
     * @param  array<int, string>  $sources
     * @return array<string, mixed>
     */
    public function getOrCreateActiveSession(string $username, array $sources = []): array
    {
        if (! $this->isAvailable()) {
            throw new RuntimeException('Tabel chat project search belum tersedia.');
        }

        $existing = $this->activeSession($username);
        if ($existing !== null) {
            return $existing;
        }

        $uuid = (string) Str::uuid();

        $id = DB::connection('project_search')
            ->table('project_search_chat_sessions')
            ->insertGetId([
                'session_uuid' => $uuid,
                'username' => $username,
                'status' => 'active',
                'sources' => json_encode($sources),
                'started_at' => now(),
                'message_count' => 0,
            ]);

        session([self::SESSION_KEY => $uuid]);

        return [
            'id' => (int) $id,
            'session_uuid' => $uuid,
            'username' => $username,
            'status' => 'active',
            'sources' => $sources,
            'started_at' => now()->toIso8601String(),
            'ended_at' => null,
            'message_count' => 0,
        ];
    }

    /**
     * @return array<int, array<string, mixed>>
     */
    public function messagesForActiveSession(string $username): array
    {
        $session = $this->activeSession($username);
        if ($session === null) {
            return [];
        }

        return $this->messagesForSessionId((int) $session['id']);
    }

    /**
     * @return array<int, array<string, mixed>>
     */
    public function messagesForSessionId(int $sessionId): array
    {
        return DB::connection('project_search')
            ->table('project_search_chat_messages')
            ->where('session_id', $sessionId)
            ->orderBy('id')
            ->get()
            ->map(fn ($row) => $this->mapMessage($row))
            ->all();
    }

    /**
     * @return array<int, array{role: string, content: string}>
     */
    public function conversationHistoryForOllama(int $sessionId): array
    {
        return DB::connection('project_search')
            ->table('project_search_chat_messages')
            ->where('session_id', $sessionId)
            ->whereIn('role', ['user', 'assistant'])
            ->orderBy('id')
            ->get(['role', 'content'])
            ->map(fn ($row) => [
                'role' => $row->role === 'assistant' ? 'assistant' : 'user',
                'content' => (string) $row->content,
            ])
            ->all();
    }

    /**
     * @return array<string, mixed>
     */
    public function addUserMessage(int $sessionId, string $content): array
    {
        $message = $this->insertMessage($sessionId, 'user', $content);

        DB::connection('project_search')
            ->table('project_search_chat_sessions')
            ->where('id', $sessionId)
            ->increment('message_count');

        return $message;
    }

    /**
     * @param  array<int, array<string, mixed>>  $results
     * @param  array<string, mixed>  $meta
     * @return array<string, mixed>
     */
    public function addAssistantMessage(int $sessionId, string $content, array $results = [], array $meta = []): array
    {
        $message = $this->insertMessage($sessionId, 'assistant', $content, $results, $meta);

        DB::connection('project_search')
            ->table('project_search_chat_sessions')
            ->where('id', $sessionId)
            ->increment('message_count');

        return $message;
    }

    public function endActiveSession(string $username): bool
    {
        $session = $this->activeSession($username);
        if ($session === null) {
            session()->forget(self::SESSION_KEY);

            return false;
        }

        DB::connection('project_search')
            ->table('project_search_chat_sessions')
            ->where('id', $session['id'])
            ->update([
                'status' => 'ended',
                'ended_at' => now(),
            ]);

        session()->forget(self::SESSION_KEY);

        return true;
    }

    /**
     * @return array<int, array<string, mixed>>
     */
    public function recentEndedSessions(string $username, int $limit = 10): array
    {
        if (! $this->isAvailable()) {
            return [];
        }

        return DB::connection('project_search')
            ->table('project_search_chat_sessions')
            ->where('username', $username)
            ->where('status', 'ended')
            ->orderByDesc('ended_at')
            ->limit($limit)
            ->get()
            ->map(fn ($row) => $this->mapSession($row))
            ->all();
    }

    /**
     * @param  array<int, array<string, mixed>>  $results
     * @param  array<string, mixed>  $meta
     * @return array<string, mixed>
     */
    private function insertMessage(int $sessionId, string $role, string $content, array $results = [], array $meta = []): array
    {
        $id = DB::connection('project_search')
            ->table('project_search_chat_messages')
            ->insertGetId([
                'session_id' => $sessionId,
                'role' => $role,
                'content' => $content,
                'results' => $results !== [] ? json_encode($results) : null,
                'meta' => $meta !== [] ? json_encode($meta) : null,
                'created_at' => now(),
            ]);

        return [
            'id' => (int) $id,
            'session_id' => $sessionId,
            'role' => $role,
            'content' => $content,
            'results' => $results,
            'meta' => $meta,
            'created_at' => now()->toIso8601String(),
        ];
    }

    /**
     * @return array<string, mixed>
     */
    private function mapSession(object $row): array
    {
        $sources = $row->sources ?? null;
        if (is_string($sources)) {
            $sources = json_decode($sources, true);
        }

        return [
            'id' => (int) $row->id,
            'session_uuid' => (string) $row->session_uuid,
            'username' => (string) $row->username,
            'status' => (string) $row->status,
            'sources' => is_array($sources) ? $sources : [],
            'started_at' => $row->started_at,
            'ended_at' => $row->ended_at,
            'message_count' => (int) $row->message_count,
        ];
    }

    /**
     * @return array<string, mixed>
     */
    private function mapMessage(object $row): array
    {
        $results = $row->results ?? null;
        $meta = $row->meta ?? null;

        if (is_string($results)) {
            $results = json_decode($results, true);
        }
        if (is_string($meta)) {
            $meta = json_decode($meta, true);
        }

        return [
            'id' => (int) $row->id,
            'session_id' => (int) $row->session_id,
            'role' => (string) $row->role,
            'content' => (string) $row->content,
            'results' => is_array($results) ? $results : [],
            'meta' => is_array($meta) ? $meta : [],
            'created_at' => $row->created_at,
        ];
    }
}