import { Injectable, Logger, NotFoundException } from '@nestjs/common';
import { PrismaService } from '../../../database/prisma.service';
import { GeminiService } from '../../gemini/gemini.service';
import { CreateSegmentDto, UpdateSegmentDto } from '../dto';
import { AnalysisService } from './analysis.service';
import { VersionsService } from './versions.service';
import {
  buildScriptOutlinePrompt,
  buildChapterSegmentPrompt,
  buildSegmentRewritePrompt,
  buildSegmentImagePrompt,
  calculateTargetWordCount,
  calculateEstimatedChapters,
} from '../prompts';

/**
 * ScriptsService
 *
 * Service for managing script segments and AI-powered script generation.
 *
 * TR: Script segmentlerini yönetmek ve AI destekli script oluşturmak için servis.
 * EN: Service for managing script segments and AI-powered script generation.
 */
@Injectable()
export class ScriptsService {
  private readonly logger = new Logger(ScriptsService.name);

  constructor(
    private readonly prisma: PrismaService,
    private readonly gemini: GeminiService,
    private readonly analysisService: AnalysisService,
    private readonly versionsService: VersionsService,
  ) {}

  /**
   * Create a new segment
   */
  async createSegment(data: CreateSegmentDto) {
    // Get highest sortOrder for this project
    const lastSegment = await this.prisma.scriptSegment.findFirst({
      where: { projectId: data.projectId },
      orderBy: { sortOrder: 'desc' },
    });

    const sortOrder = data.sortOrder ?? (lastSegment?.sortOrder ?? 0) + 1;

    return this.prisma.scriptSegment.create({
      data: {
        ...data,
        sortOrder,
        citationIndexes: [],
      },
    });
  }

  /**
   * Update a segment
   */
  async updateSegment(id: string, data: UpdateSegmentDto) {
    const segment = await this.prisma.scriptSegment.findUnique({
      where: { id },
    });
    if (!segment) {
      throw new NotFoundException(`Segment with ID ${id} not found`);
    }

    return this.prisma.scriptSegment.update({
      where: { id },
      data,
    });
  }

  /**
   * Delete a segment
   */
  async deleteSegment(id: string) {
    const segment = await this.prisma.scriptSegment.findUnique({
      where: { id },
    });
    if (!segment) {
      throw new NotFoundException(`Segment with ID ${id} not found`);
    }

    return this.prisma.scriptSegment.delete({ where: { id } });
  }

  /**
   * Reorder segments
   *
   * @param projectId - Project ID
   * @param segmentIds - Array of segment IDs in new order
   */
  async reorderSegments(projectId: string, segmentIds: string[]) {
    const updates = segmentIds.map((id, index) =>
      this.prisma.scriptSegment.update({
        where: { id },
        data: { sortOrder: index },
      }),
    );

    await this.prisma.$transaction(updates);

    return this.prisma.scriptSegment.findMany({
      where: { projectId },
      orderBy: { sortOrder: 'asc' },
    });
  }

  /**
   * Generate a full script for a project
   *
   * @param projectId - Project ID
   * @returns Generated segments
   */
  async generateScript(projectId: string) {
    this.logger.log(`Generating script for project: ${projectId}`);

    // Auto-snapshot current state before regeneration
    await this.versionsService.createSnapshot(
      projectId,
      'AUTO_SAVE',
      undefined,
      'Auto-save before script generation',
    ).catch(() => { /* ignore if no segments yet */ });

    // Update status
    await this.prisma.scriptProject.update({
      where: { id: projectId },
      data: { status: 'SCRIPTING' },
    });

    const project = await this.prisma.scriptProject.findUnique({
      where: { id: projectId },
      include: {
        sources: { where: { selected: true } },
        briefItems: { orderBy: { sortOrder: 'asc' } },
        characters: true,
      },
    });

    if (!project) {
      throw new NotFoundException(`Project with ID ${projectId} not found`);
    }

    // Build context from project data
    const sourceContext = project.sources
      .slice(0, 5)
      .map((s, i) => `[Source ${i + 1}] (${s.type}): ${s.title} - ${s.snippet}`)
      .join('\n');

    const briefContext = project.briefItems
      .map((b) => `Q: ${b.question}\nA: ${b.answer}`)
      .join('\n');

    const characterContext = project.characters
      .map(
        (c) =>
          `${c.name} (${c.role}): Values[${c.values}] Traits[${c.traits}] Mannerisms[${c.mannerisms}]`,
      )
      .join('\n');

    // Calculate target metrics
    const targetWordCount = calculateTargetWordCount(project.targetDuration);
    const estimatedChapters = calculateEstimatedChapters(targetWordCount);

    // PHASE 1: Generate Outline using prompt builder
    const outlinePromptData = buildScriptOutlinePrompt({
      topic: project.topic,
      logline: project.logline || '',
      characterContext,
      speechStyles: project.speechStyle,
      targetAudience: project.targetAudience,
      contentType: project.contentType,
      targetDuration: project.targetDuration,
      targetWordCount,
      estimatedChapters,
      sourceContext,
      briefContext,
    });

    const outlineResp = await this.gemini.generateJSON<{
      title: string;
      seoDescription: string;
      tags: string[];
      thumbnailIdeas: string[];
      chapters: { title: string; focus: string; type: string }[];
    }>(outlinePromptData.prompt, outlinePromptData.schema, {
      temperature: outlinePromptData.temperature,
    });

    const outlineData = outlineResp.data;

    // Update project with SEO data
    await this.prisma.scriptProject.update({
      where: { id: projectId },
      data: {
        seoTitle: outlineData.title,
        seoDescription: outlineData.seoDescription,
        seoTags: outlineData.tags,
        thumbnailIdeas: outlineData.thumbnailIdeas,
      },
    });

    // PHASE 2: Generate each chapter using prompt builder
    const generatedSegments: any[] = [];
    let timeOffset = 0;

    for (let i = 0; i < outlineData.chapters.length; i++) {
      const chapter = outlineData.chapters[i];

      const chapterPromptData = buildChapterSegmentPrompt({
        chapterIndex: i,
        totalChapters: outlineData.chapters.length,
        chapterTitle: chapter.title,
        chapterFocus: chapter.focus,
        chapterType: chapter.type,
        speechStyles: project.speechStyle,
        targetAudience: project.targetAudience,
        characterContext,
        language: project.language,
      });

      try {
        const segmentResp = await this.gemini.generateJSON<any[]>(
          chapterPromptData.prompt,
          chapterPromptData.schema,
          { temperature: chapterPromptData.temperature },
        );

        for (const seg of segmentResp.data) {
          const words = seg.narratorScript
            ? seg.narratorScript.split(' ').length
            : 0;
          const dur = Math.max(5, Math.ceil(words / (140 / 60)));
          const start = this.formatTime(timeOffset);
          timeOffset += dur;

          generatedSegments.push({
            projectId,
            segmentType: seg.segmentType || 'Body',
            timeStart: start,
            duration: `${dur}s`,
            narratorScript: seg.narratorScript || '',
            visualDescription: seg.visualDescription || 'Background',
            videoPrompt:
              seg.videoPrompt || `Cinematic shot of ${seg.stockQuery}`,
            imagePrompt:
              seg.imagePrompt || `High quality image of ${seg.stockQuery}`,
            onScreenText: seg.onScreenText || '',
            editorNotes: '',
            generalNotes: '',
            audioCues: seg.audioCues || '',
            stockQuery: seg.stockQuery || 'background',
            sortOrder: generatedSegments.length,
            citationIndexes: [],
          });
        }
      } catch (error) {
        this.logger.warn(`Failed to generate chapter ${i + 1}: ${error}`);
      }
    }

    // Clear existing segments and insert new ones
    await this.prisma.scriptSegment.deleteMany({ where: { projectId } });

    if (generatedSegments.length > 0) {
      await this.prisma.scriptSegment.createMany({
        data: generatedSegments,
      });
    }

    return this.prisma.scriptSegment.findMany({
      where: { projectId },
      orderBy: { sortOrder: 'asc' },
    });
  }

  /**
   * Rewrite a segment with a new style
   *
   * @param segmentId - Segment ID
   * @param newStyle - New speech style
   * @returns Updated segment
   */
  async rewriteSegment(
    segmentId: string,
    newStyle: string, // SpeechStyle or 'Make it Longer' | 'Make it Shorter'
  ) {
    const segment = await this.prisma.scriptSegment.findUnique({
      where: { id: segmentId },
      include: { project: true },
    });

    if (!segment) {
      throw new NotFoundException(`Segment with ID ${segmentId} not found`);
    }

    const promptData = buildSegmentRewritePrompt({
      currentScript: segment.narratorScript || '',
      newStyle,
      topic: segment.project.topic,
      language: segment.project.language,
    });

    const rewriteResp = await this.gemini.generateJSON<{
      narratorScript: string;
      visualDescription: string;
      onScreenText: string;
      audioCues: string;
    }>(promptData.prompt, promptData.schema, {
      temperature: promptData.temperature,
    });

    const data = rewriteResp.data;
    const words = data.narratorScript
      ? data.narratorScript.split(' ').length
      : 0;
    const dur = Math.max(5, Math.ceil(words / (140 / 60)));

    return this.prisma.scriptSegment.update({
      where: { id: segmentId },
      data: {
        narratorScript: data.narratorScript,
        visualDescription: data.visualDescription,
        onScreenText: data.onScreenText,
        audioCues: data.audioCues,
        duration: `${dur}s`,
      },
    });
  }

  /**
   * Format seconds to MM:SS
   */
  private formatTime(seconds: number): string {
    const m = Math.floor(seconds / 60);
    const s = seconds % 60;
    return `${m.toString().padStart(2, '0')}:${s.toString().padStart(2, '0')}`;
  }

  /**
   * Generate an image for a specific segment
   */
  async generateSegmentImage(segmentId: string) {
    const segment = await this.prisma.scriptSegment.findUnique({
      where: { id: segmentId },
      include: { project: true },
    });

    if (!segment) {
      throw new NotFoundException(`Segment with ID ${segmentId} not found`);
    }

    // 1. Generate/Refine Image Prompt using LLM
    const promptData = buildSegmentImagePrompt({
      topic: segment.project.topic,
      narratorScript: segment.narratorScript || '',
      visualDescription: segment.visualDescription || '',
    });

    const prompts = await this.gemini.generateJSON<{
      imagePrompt: string;
      videoPrompt: string;
    }>(promptData.prompt, promptData.schema, {
      temperature: promptData.temperature,
    });

    // 2. Use the new image prompt for generation
    const imageUrl = await this.analysisService.generateThumbnailImage(
      prompts.data.imagePrompt,
    );

    // 3. Update segment with new prompts AND generated image URL
    return this.prisma.scriptSegment.update({
      where: { id: segmentId },
      data: {
        imagePrompt: prompts.data.imagePrompt,
        videoPrompt: prompts.data.videoPrompt,
        generatedImageUrl: imageUrl,
      },
    });
  }

  // ========== REGENERATE (Tek segment / Partial) ==========

  /**
   * Regenerate a single segment with AI.
   * Auto-snapshots current state before regeneration.
   *
   * @param segmentId - Segment ID to regenerate
   * @returns Updated segment
   */
  async regenerateSegment(segmentId: string) {
    const segment = await this.prisma.scriptSegment.findUnique({
      where: { id: segmentId },
      include: { project: { include: { characters: true } } },
    });

    if (!segment) {
      throw new NotFoundException(`Segment with ID ${segmentId} not found`);
    }

    // Auto-snapshot before regeneration
    await this.versionsService.createSnapshot(
      segment.projectId,
      'AUTO_SAVE',
      undefined,
      `Auto-save before regenerating segment #${segment.sortOrder + 1}`,
    ).catch(() => {});

    const characterContext = segment.project.characters
      .map((c) => `${c.name} (${c.role}): Values[${c.values}] Traits[${c.traits}]`)
      .join('\n');

    const chapterPromptData = buildChapterSegmentPrompt({
      chapterIndex: segment.sortOrder,
      totalChapters: 1,
      chapterTitle: segment.segmentType,
      chapterFocus: segment.visualDescription || segment.segmentType,
      chapterType: segment.segmentType,
      speechStyles: segment.project.speechStyle,
      targetAudience: segment.project.targetAudience,
      characterContext,
      language: segment.project.language,
    });

    const resp = await this.gemini.generateJSON<any[]>(
      chapterPromptData.prompt,
      chapterPromptData.schema,
      { temperature: chapterPromptData.temperature },
    );

    const newSeg = resp.data[0];
    if (!newSeg) return segment;

    const words = newSeg.narratorScript ? newSeg.narratorScript.split(' ').length : 0;
    const dur = Math.max(5, Math.ceil(words / (140 / 60)));

    return this.prisma.scriptSegment.update({
      where: { id: segmentId },
      data: {
        narratorScript: newSeg.narratorScript,
        visualDescription: newSeg.visualDescription,
        videoPrompt: newSeg.videoPrompt,
        imagePrompt: newSeg.imagePrompt,
        onScreenText: newSeg.onScreenText,
        audioCues: newSeg.audioCues,
        stockQuery: newSeg.stockQuery,
        duration: `${dur}s`,
      },
    });
  }

  /**
   * Regenerate multiple selected segments.
   *
   * @param projectId - Project ID
   * @param segmentIds - Array of segment IDs to regenerate
   * @returns Updated segments
   */
  async regeneratePartial(projectId: string, segmentIds: string[]) {
    // Auto-snapshot
    await this.versionsService.createSnapshot(
      projectId,
      'AUTO_SAVE',
      undefined,
      `Auto-save before partial regeneration (${segmentIds.length} segments)`,
    ).catch(() => {});

    const results: any[] = [];
    for (const segId of segmentIds) {
      try {
        const result = await this.regenerateSegment(segId);
        results.push(result);
      } catch (error) {
        this.logger.warn(`Failed to regenerate segment ${segId}: ${error}`);
      }
    }

    return results;
  }
}