<?php

namespace App\Services\Document;

use App\Jobs\ReindexChunkJob;
use App\Models\ChunkAudit;
use App\Models\DocumentChunk;
use App\Services\KnowledgeBase\AuditService;
use App\Services\Qdrant\QdrantService;
use Illuminate\Support\Facades\DB;
use RuntimeException;

/**
 * ChunkEditingService
 *
 * Menguruskan operasi edit dan toggle status untuk satu chunk:
 *   - Edit final_text
 *   - Exclude chunk dari indexing
 *   - Include semula chunk ke indexing
 *
 * Setiap operasi:
 *   1. Kemaskini rekod MySQL
 *   2. Sync status ke Qdrant jika perlu
 *   3. Rekod chunk_audits
 *   4. Log ke audit_logs
 *   5. Dispatch ReindexChunkJob jika perlu
 */
class ChunkEditingService
{
    public function __construct(
        private readonly QdrantService $qdrant,
        private readonly AuditService  $audit,
    ) {}

    // =========================================================================
    // EDIT FINAL TEXT
    // =========================================================================

    /**
     * Edit final_text sebuah chunk.
     *
     * Raw_text (content) tidak disentuh.
     * Selepas edit, chunk ditandakan needs_reindex dan ReindexChunkJob diantrikan.
     *
     * @throws RuntimeException Jika chunk tidak boleh diedit (e.g. superseded)
     */
    public function editFinalText(
        DocumentChunk $chunk,
        string $newFinalText,
        ?string $notes = null
    ): void {
        if ($chunk->isSuperseded()) {
            throw new RuntimeException(
                'Chunk yang telah digantikan (superseded) tidak boleh diedit.'
            );
        }

        $oldFinalText = $chunk->final_text;
        $oldStatus    = $chunk->chunk_status;

        DB::transaction(function () use ($chunk, $newFinalText, $notes, $oldFinalText, $oldStatus) {
            $chunk->update([
                'final_text'    => $newFinalText,
                'is_edited'     => true,
                'chunk_status'  => DocumentChunk::STATUS_NEEDS_REINDEX,
                'needs_reindex' => true,
                'edited_by'     => auth()->id(),
                'edited_at'     => now(),
            ]);

            ChunkAudit::record($chunk->id, ChunkAudit::OP_EDIT_FINAL_TEXT, [
                'old_final_text' => $oldFinalText,
                'new_final_text' => $newFinalText,
                'old_status'     => $oldStatus,
                'new_status'     => DocumentChunk::STATUS_NEEDS_REINDEX,
                'metadata'       => [
                    'word_count_before' => str_word_count($oldFinalText ?? $chunk->content),
                    'word_count_after'  => str_word_count($newFinalText),
                    'char_count_before' => mb_strlen($oldFinalText ?? $chunk->content),
                    'char_count_after'  => mb_strlen($newFinalText),
                ],
            ], $notes);
        });

        $this->audit->chunkFinalTextEdited($chunk, $oldFinalText, $newFinalText);

        // Hantar ke queue untuk reindex
        ReindexChunkJob::dispatch($chunk->id);
    }

    // =========================================================================
    // EXCLUDE / INCLUDE
    // =========================================================================

    /**
     * Kecualikan chunk dari indexing.
     *
     * - is_active = false
     * - chunk_status = 'excluded'
     * - Qdrant point ditandakan tidak aktif (jika ada)
     */
    public function excludeChunk(DocumentChunk $chunk, ?string $notes = null): void
    {
        if ($chunk->chunk_status === DocumentChunk::STATUS_EXCLUDED) {
            return; // Sudah excluded — tidak perlu buat apa-apa
        }

        if ($chunk->isSuperseded()) {
            throw new RuntimeException(
                'Chunk superseded tidak boleh di-exclude secara manual.'
            );
        }

        $oldStatus = $chunk->chunk_status;

        DB::transaction(function () use ($chunk, $notes, $oldStatus) {
            $chunk->markAsExcluded();

            // Deactivate di Qdrant jika ada point
            if ($chunk->qdrant_point_id) {
                $this->qdrant->updatePayload($chunk->qdrant_point_id, [
                    'is_active' => false,
                    'status'    => 'excluded',
                ]);
            }

            ChunkAudit::record($chunk->id, ChunkAudit::OP_EXCLUDE, [
                'old_status' => $oldStatus,
                'new_status' => DocumentChunk::STATUS_EXCLUDED,
            ], $notes);
        });

        $this->audit->chunkExcluded($chunk, $oldStatus);
    }

    /**
     * Kembalikan chunk ke indexing.
     *
     * - is_active = true
     * - exclude_from_index = false
     * - Jika sudah embedded: reactivate di Qdrant + status kembali 'indexed'
     * - Jika belum embedded: queue reindex
     *
     * @throws RuntimeException Jika chunk adalah superseded (tidak boleh di-include)
     */
    public function includeChunk(DocumentChunk $chunk, ?string $notes = null): void
    {
        if ($chunk->isSuperseded()) {
            throw new RuntimeException(
                'Chunk yang telah digantikan (superseded) tidak boleh dikembalikan. '
                . 'Gunakan child chunks yang dihasilkan dari split.'
            );
        }

        if (! $chunk->exclude_from_index && $chunk->is_active) {
            return; // Sudah active — tidak perlu buat apa-apa
        }

        $oldStatus = $chunk->chunk_status;

        DB::transaction(function () use ($chunk, $notes, $oldStatus) {
            $chunk->markAsIncluded();

            // Jika ada Qdrant point, aktifkan semula
            if ($chunk->qdrant_point_id && $chunk->is_embedded) {
                $this->qdrant->updatePayload($chunk->qdrant_point_id, [
                    'is_active' => true,
                    'status'    => 'active',
                ]);
            }

            ChunkAudit::record($chunk->id, ChunkAudit::OP_INCLUDE, [
                'old_status' => $oldStatus,
                'new_status' => $chunk->fresh()->chunk_status,
            ], $notes);
        });

        $this->audit->chunkIncluded($chunk, $oldStatus);

        // Queue reindex jika chunk belum embedded atau final_text berubah
        if ($chunk->fresh()->needs_reindex) {
            ReindexChunkJob::dispatch($chunk->id);
        }
    }

    // =========================================================================
    // TRIGGER REINDEX
    // =========================================================================

    /**
     * Tandakan chunk perlu reindex dan dispatch job.
     * Digunakan oleh admin apabila mahu refresh embedding tanpa edit teks.
     */
    public function triggerReindex(DocumentChunk $chunk, ?string $notes = null): void
    {
        if (! $chunk->isIndexable()) {
            throw new RuntimeException(
                'Chunk ini tidak boleh direindex (status: ' . $chunk->chunk_status . ').'
            );
        }

        $oldStatus = $chunk->chunk_status;

        $chunk->update([
            'chunk_status'  => DocumentChunk::STATUS_NEEDS_REINDEX,
            'needs_reindex' => true,
        ]);

        ChunkAudit::record($chunk->id, ChunkAudit::OP_REINDEX, [
            'old_status' => $oldStatus,
            'new_status' => DocumentChunk::STATUS_NEEDS_REINDEX,
        ], $notes);

        $this->audit->chunkReindexTriggered($chunk);

        ReindexChunkJob::dispatch($chunk->id);
    }
}