<?php
declare(strict_types=1);

class NormalBot
{
    public static function process(array $company, array $context, string $input): ?array
    {
        $config = self::getConfig($company);
        $commands = $config['commands'] ?? [];
        $flows    = $config['flows'] ?? [];
        $menus    = $config['menus'] ?? [];

        $ctxId = null;
        $botCtx = ConversationContext::getOrCreate((int)$company['id'], $context['from'], 'normal');
        $ctxId = (int)$botCtx['id'];
        $currentNode = $botCtx['current_node'];

        $normalized = self::normalize($input);

        if ($currentNode !== null && isset($flows[$currentNode])) {
            return self::handleFlow($flows[$currentNode], $context, $company, $ctxId);
        }

        $matchedCommand = null;
        foreach ($commands as $keyword => $action) {
            if ($normalized === self::normalize($keyword)) {
                $matchedCommand = $action;
                break;
            }
        }

        if ($matchedCommand !== null) {
            ConversationContext::updateNode($ctxId, $matchedCommand);

            if (isset($flows[$matchedCommand])) {
                return self::handleFlow($flows[$matchedCommand], $context, $company, $ctxId);
            }

            if (isset($menus[$matchedCommand])) {
                return self::buildMenuResponse($menus[$matchedCommand], $context['from'], $company);
            }

            return null;
        }

        $greeting = $config['greeting'] ?? null;
        if ($greeting !== null && $currentNode === null) {
            ConversationContext::updateNode($ctxId, 'greeting');

            if (isset($flows['greeting'])) {
                return self::handleFlow($flows['greeting'], $context, $company, $ctxId);
            }

            return self::sendText($greeting, $context['from'], $company);
        }

        $fallback = $config['fallback'] ?? null;
        if ($fallback !== null) {
            return self::sendText($fallback, $context['from'], $company);
        }

        return null;
    }

    private static function handleFlow(array $flow, array $context, array $company, int $ctxId): ?array
    {
        $type = $flow['type'] ?? 'text';

        return match ($type) {
            'text' => self::sendText($flow['message'] ?? '', $context['from'], $company),
            'image' => self::sendImage($flow['media_id'] ?? '', $flow['caption'] ?? null, $context['from'], $company),
            'menu' => self::buildMenuResponse($flow['menu'] ?? [], $context['from'], $company),
            'function' => self::executeFunction($flow['function'] ?? '', $flow['params'] ?? [], $context, $company, $ctxId),
            default => null,
        };
    }

    private static function executeFunction(string $function, array $params, array $context, array $company, int $ctxId): ?array
    {
        return match ($function) {
            'reset' => (function () use ($ctxId, $context, $company) {
                ConversationContext::reset($ctxId);
                return self::sendText('¿En qué más puedo ayudarte?', $context['from'], $company);
            })(),
            'forward_to_ai' => null,
            default => null,
        };
    }

    private static function buildMenuResponse(array $menu, string $to, array $company): array
    {
        $menuType = $menu['type'] ?? 'list';

        if ($menuType === 'list') {
            $interactive = [
                'type' => 'list',
                'header' => [
                    'type' => 'text',
                    'text' => mb_substr($menu['header'] ?? 'Menú', 0, 60),
                ],
                'body' => [
                    'text' => mb_substr($menu['body'] ?? 'Selecciona una opción:', 0, 1024),
                ],
                'footer' => [
                    'text' => mb_substr($menu['footer'] ?? $company['display_name'] ?? '', 0, 60),
                ],
                'action' => [
                    'button' => mb_substr($menu['button'] ?? 'Ver opciones', 0, 20),
                    'sections' => [],
                ],
            ];

            foreach ($menu['sections'] ?? [] as $section) {
                $rows = [];
                foreach ($section['rows'] ?? [] as $row) {
                    $rows[] = [
                        'id' => mb_substr($row['id'] ?? '', 0, 200),
                        'title' => mb_substr($row['title'] ?? '', 0, 24),
                        'description' => isset($row['description']) ? mb_substr($row['description'], 0, 72) : null,
                    ];
                }
                $interactive['action']['sections'][] = [
                    'title' => mb_substr($section['title'] ?? '', 0, 24),
                    'rows' => $rows,
                ];
            }

            return self::enqueueInteractive($to, $interactive, $company);
        }

        if ($menuType === 'buttons') {
            $buttons = [];
            foreach ($menu['buttons'] ?? [] as $btn) {
                $buttons[] = [
                    'type' => 'reply',
                    'reply' => [
                        'id' => mb_substr($btn['id'] ?? '', 0, 256),
                        'title' => mb_substr($btn['title'] ?? '', 0, 20),
                    ],
                ];
            }

            $interactive = [
                'type' => 'button',
                'body' => [
                    'text' => mb_substr($menu['body'] ?? 'Selecciona:', 0, 1024),
                ],
                'action' => ['buttons' => $buttons],
            ];

            return self::enqueueInteractive($to, $interactive, $company);
        }

        return null;
    }

    private static function sendText(string $text, string $to, array $company): array
    {
        return [
            'action' => 'send',
            'type' => 'text',
            'to' => $to,
            'payload' => json_encode(['text' => $text]),
        ];
    }

    private static function sendImage(string $mediaId, ?string $caption, string $to, array $company): array
    {
        return [
            'action' => 'send',
            'type' => 'image',
            'to' => $to,
            'payload' => json_encode(['media_id' => $mediaId, 'caption' => $caption]),
        ];
    }

    private static function enqueueInteractive(string $to, array $interactive, array $company): array
    {
        return [
            'action' => 'send',
            'type' => 'interactive',
            'to' => $to,
            'payload' => json_encode(['interactive' => $interactive]),
        ];
    }

    private static function getConfig(array $company): array
    {
        $json = $company['config_json'] ?? '';
        if ($json === '') {
            return [];
        }
        $config = json_decode($json, true);
        return is_array($config) ? $config : [];
    }

    private static function normalize(string $input): string
    {
        $input = mb_strtolower(trim($input));
        $input = str_replace(['á', 'é', 'í', 'ó', 'ú', 'ü', 'ñ'], ['a', 'e', 'i', 'o', 'u', 'u', 'n'], $input);
        return preg_replace('/[^a-z0-9\s]/', '', $input);
    }

    public static function processInteractive(array $company, array $context, string $input): ?array
    {
        $config = self::getConfig($company);
        $flows = $config['flows'] ?? [];

        $botCtx = ConversationContext::getOrCreate((int)$company['id'], $context['from'], 'normal');
        $ctxId = (int)$botCtx['id'];

        foreach ($flows as $flowId => $flow) {
            if (($flow['type'] ?? '') === 'menu') {
                $menu = $flow['menu'] ?? [];
                foreach ($menu['sections'] ?? [] as $section) {
                    foreach ($section['rows'] ?? [] as $row) {
                        if (($row['id'] ?? '') === $input) {
                            ConversationContext::updateNode($ctxId, $row['id']);
                            if (isset($flows[$row['id']])) {
                                return self::handleFlow($flows[$row['id']], $context, $company, $ctxId);
                            }
                            return null;
                        }
                    }
                }
                foreach ($menu['buttons'] ?? [] as $btn) {
                    if (($btn['id'] ?? '') === $input) {
                        ConversationContext::updateNode($ctxId, $btn['id']);
                        if (isset($flows[$btn['id']])) {
                            return self::handleFlow($flows[$btn['id']], $context, $company, $ctxId);
                        }
                        return null;
                    }
                }
            }
        }

        return null;
    }
}