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

/**
 * Vue built-in components — skipped so a `<Transition>` / `<KeepAlive>` in the
 * template doesn't become a phantom reference to a user component. Checked
 * AFTER kebab→Pascal conversion, so `<keep-alive>` is caught here too.
 */
const VUE_BUILTIN_COMPONENTS = new Set([
  'Transition',
  'TransitionGroup',
  'KeepAlive',
  'Suspense',
  'Teleport',
  'Component',
  'Slot',
]);

/** `my-component` → `MyComponent` (Vue allows either form in templates). */
function kebabToPascal(name: string): string {
  return name
    .split('-')
    .map((part) => (part ? part[0]!.toUpperCase() + part.slice(1) : ''))
    .join('');
}

/**
 * VueExtractor - Extracts code relationships from Vue Single-File Component files
 *
 * Vue SFCs are multi-language (script + template + style). Rather than
 * parsing the full Vue grammar, we extract the <script> block content
 * and delegate it to the TypeScript/JavaScript TreeSitterExtractor.
 *
 * Every .vue file produces a component node (Vue components are always importable).
 */
export class VueExtractor {
  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 Vue source
   */
  extract(): ExtractionResult {
    const startTime = Date.now();

    try {
      // Create component node for the .vue 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);
      }

      // Extract component usages from the <template> (<ComponentName>).
      // Without this, a Vue component used only in another component's
      // markup (incl. through a barrel import) is invisible to callers /
      // impact (#629 follow-up).
      this.extractTemplateComponents(componentNode.id);
    } catch (error) {
      this.errors.push({
        message: `Vue 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 .vue file
   */
  private createComponentNode(): Node {
    const lines = this.source.split('\n');
    const fileName = this.filePath.split(/[/\\]/).pop() || this.filePath;
    const componentName = fileName.replace(/\.vue$/, '');
    const id = generateNodeId(this.filePath, 'component', componentName, 1);

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

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

  /**
   * Extract <script> and <script setup> blocks from the Vue source
   */
  private extractScriptBlocks(): Array<{
    content: string;
    startLine: number;
    isSetup: boolean;
    isTypeScript: boolean;
  }> {
    const blocks: Array<{
      content: string;
      startLine: number;
      isSetup: 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 <script setup>
      const isSetup = /\bsetup\b/.test(attrs);

      // Calculate the 0-indexed line where the content begins. The content
      // starts right after the opening tag's `>` — its leading `\n` is part
      // of the content, so relative line 1 sits ON the tag's closing line
      // (adding 1 here double-counted the embedded newline and shifted every
      // script-block symbol down a line).
      const beforeScript = this.source.substring(0, match.index);
      const scriptTagLine = (beforeScript.match(/\n/g) || []).length;
      const openingTag = match[0].substring(0, match[0].indexOf('>') + 1);
      const openingTagLines = (openingTag.match(/\n/g) || []).length;
      const contentStartLine = scriptTagLine + openingTagLines; // 0-indexed line

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

    return blocks;
  }

  /**
   * Process a script block by delegating to TreeSitterExtractor
   */
  private processScriptBlock(
    block: { content: string; startLine: number; isSetup: 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 Vue 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 .vue file positions
    for (const node of result.nodes) {
      node.startLine += block.startLine;
      node.endLine += block.startLine;
      node.language = 'vue'; // Mark as vue, 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 = 'vue';
      this.unresolvedReferences.push(ref);
    }

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

  /**
   * Extract component usages from the Vue `<template>`.
   *
   * PascalCase tags (`<Modal>`, `<Button />`) and kebab-case tags
   * (`<my-button>`) both represent component instantiations — analogous to
   * function calls in imperative code. Capturing them creates parent→child
   * component edges and lets `callers` / `impact` see a component that is
   * only ever used in markup. Vue's extractor previously parsed only the
   * `<script>` block, so these usages produced no edge at all (#629).
   *
   * HTML elements (lowercase, no hyphen) and Vue built-ins are skipped.
   * Unmatched names create no edge during resolution, so converting
   * kebab-case is safe even for native custom elements.
   */
  private extractTemplateComponents(componentNodeId: string): void {
    // Ranges covered by <script> / <style> blocks — skip them so script
    // identifiers and CSS selectors aren't mistaken for template tags. This
    // also correctly handles nested <template> tags (v-if / slots), which a
    // single non-greedy <template>…</template> match would mis-bound.
    const coveredRanges: Array<[number, number]> = [];
    const blockRegex = /<(script|style)(\s[^>]*)?>[\s\S]*?<\/\1>/g;
    let blockMatch;
    while ((blockMatch = blockRegex.exec(this.source)) !== null) {
      const startLine = (this.source.substring(0, blockMatch.index).match(/\n/g) || []).length;
      const endLine = startLine + (blockMatch[0].match(/\n/g) || []).length;
      coveredRanges.push([startLine, endLine]);
    }

    const lines = this.source.split('\n');
    // Opening / self-closing tags (closing `</Foo>` starts with `</`, so the
    // leading `<` followed by a name letter won't match it).
    const tagRegex = /<([A-Za-z][A-Za-z0-9_-]*)\b/g;

    for (let lineIdx = 0; lineIdx < lines.length; lineIdx++) {
      if (coveredRanges.some(([start, end]) => lineIdx >= start && lineIdx <= end)) continue;

      const line = lines[lineIdx]!;
      let match;
      while ((match = tagRegex.exec(line)) !== null) {
        const raw = match[1]!;
        let componentName: string;
        if (/^[A-Z]/.test(raw)) {
          componentName = raw; // PascalCase component
        } else if (raw.includes('-')) {
          componentName = kebabToPascal(raw); // kebab-case component
        } else {
          continue; // lowercase, no hyphen → native HTML element
        }
        if (VUE_BUILTIN_COMPONENTS.has(componentName)) continue;

        this.unresolvedReferences.push({
          fromNodeId: componentNodeId,
          referenceName: componentName,
          referenceKind: 'references',
          line: lineIdx + 1, // 1-indexed
          column: match.index + 1,
          filePath: this.filePath,
          language: 'vue',
        });
      }
    }
  }
}
