import { Node, Edge, ExtractionResult, ExtractionError, UnresolvedReference, Language } from '../types';
import { generateNodeId } from './tree-sitter-helpers';
import { TreeSitterExtractor } from './tree-sitter';
import { isLanguageSupported } from './grammars';

/**
 * SvelteExtractor - Extracts code relationships from Svelte component files
 *
 * Svelte files are multi-language (script + template + style). Rather than
 * parsing the full Svelte grammar, we extract the <script> block content
 * and delegate it to the TypeScript/JavaScript TreeSitterExtractor.
 *
 * Every .svelte file produces a component node (Svelte components are always importable).
 */
export class SvelteExtractor {
  private filePath: string;
  private source: string;
  private nodes: Node[] = [];
  private edges: Edge[] = [];
  private unresolvedReferences: UnresolvedReference[] = [];
  private errors: ExtractionError[] = [];

  constructor(filePath: string, source: string) {
    this.filePath = filePath;
    this.source = source;
  }

  /**
   * Extract from Svelte source
   */
  extract(): ExtractionResult {
    const startTime = Date.now();

    try {
      // Create component node for the .svelte file itself
      const componentNode = this.createComponentNode();

      // Extract and process script blocks
      const scriptBlocks = this.extractScriptBlocks();

      for (const block of scriptBlocks) {
        this.processScriptBlock(block, componentNode.id);
      }
    } catch (error) {
      this.errors.push({
        message: `Svelte extraction error: ${error instanceof Error ? error.message : String(error)}`,
        severity: 'error',
      });
    }

    return {
      nodes: this.nodes,
      edges: this.edges,
      unresolvedReferences: this.unresolvedReferences,
      errors: this.errors,
      durationMs: Date.now() - startTime,
    };
  }

  /**
   * Create a component node for the .svelte file
   */
  private createComponentNode(): Node {
    const lines = this.source.split('\n');
    const fileName = this.filePath.split(/[/\\]/).pop() || this.filePath;
    const componentName = fileName.replace(/\.svelte$/, '');
    const id = generateNodeId(this.filePath, 'component', componentName, 1);

    const node: Node = {
      id,
      kind: 'component',
      name: componentName,
      qualifiedName: `${this.filePath}::${componentName}`,
      filePath: this.filePath,
      language: 'svelte',
      startLine: 1,
      endLine: lines.length,
      startColumn: 0,
      endColumn: lines[lines.length - 1]?.length || 0,
      isExported: true, // Svelte components are always importable
      updatedAt: Date.now(),
    };

    this.nodes.push(node);
    return node;
  }

  /**
   * Extract <script> blocks from the Svelte source
   */
  private extractScriptBlocks(): Array<{
    content: string;
    startLine: number;
    isModule: boolean;
    isTypeScript: boolean;
  }> {
    const blocks: Array<{
      content: string;
      startLine: number;
      isModule: boolean;
      isTypeScript: boolean;
    }> = [];

    const scriptRegex = /<script(\s[^>]*)?>(?<content>[\s\S]*?)<\/script>/g;
    let match;

    while ((match = scriptRegex.exec(this.source)) !== null) {
      const attrs = match[1] || '';
      const content = match.groups?.content || match[2] || '';

      // Detect TypeScript from lang attribute
      const isTypeScript = /lang\s*=\s*["'](ts|typescript)["']/.test(attrs);

      // Detect module script
      const isModule = /context\s*=\s*["']module["']/.test(attrs);

      // Calculate start line of the script content (line after <script>)
      const beforeScript = this.source.substring(0, match.index);
      const scriptTagLine = (beforeScript.match(/\n/g) || []).length;
      // The content starts on the line after the opening <script> tag
      const openingTag = match[0].substring(0, match[0].indexOf('>') + 1);
      const openingTagLines = (openingTag.match(/\n/g) || []).length;
      const contentStartLine = scriptTagLine + openingTagLines + 1; // 0-indexed line

      blocks.push({
        content,
        startLine: contentStartLine,
        isModule,
        isTypeScript,
      });
    }

    return blocks;
  }

  /**
   * Process a script block by delegating to TreeSitterExtractor
   */
  private processScriptBlock(
    block: { content: string; startLine: number; isModule: boolean; isTypeScript: boolean },
    componentNodeId: string
  ): void {
    const scriptLanguage: Language = block.isTypeScript ? 'typescript' : 'javascript';

    // Check if the script language parser is available
    if (!isLanguageSupported(scriptLanguage)) {
      this.errors.push({
        message: `Parser for ${scriptLanguage} not available, cannot parse Svelte script block`,
        severity: 'warning',
      });
      return;
    }

    // Delegate to TreeSitterExtractor
    const extractor = new TreeSitterExtractor(this.filePath, block.content, scriptLanguage);
    const result = extractor.extract();

    // Offset line numbers from script block back to .svelte file positions
    for (const node of result.nodes) {
      node.startLine += block.startLine;
      node.endLine += block.startLine;
      node.language = 'svelte'; // Mark as svelte, not TS/JS

      this.nodes.push(node);

      // Add containment edge from component to this node
      this.edges.push({
        source: componentNodeId,
        target: node.id,
        kind: 'contains',
      });
    }

    // Offset edges (they reference line numbers)
    for (const edge of result.edges) {
      if (edge.line) {
        edge.line += block.startLine;
      }
      this.edges.push(edge);
    }

    // Offset unresolved references
    for (const ref of result.unresolvedReferences) {
      ref.line += block.startLine;
      ref.filePath = this.filePath;
      ref.language = 'svelte';
      this.unresolvedReferences.push(ref);
    }

    // Carry over errors
    for (const error of result.errors) {
      if (error.line) {
        error.line += block.startLine;
      }
      this.errors.push(error);
    }
  }
}