/**
 * Internal protocol constants and utilities for improved TAP communication
 * between tapbundle and tstest
 */

export const PROTOCOL = {
  VERSION: '2.0',
  MARKERS: {
    START: '⟦TSTEST:',
    END: '⟧',
    BLOCK_END: '⟦/TSTEST:',
  },
  TYPES: {
    META: 'META',
    ERROR: 'ERROR',
    SKIP: 'SKIP',
    TODO: 'TODO',
    SNAPSHOT: 'SNAPSHOT',
    PROTOCOL: 'PROTOCOL',
  }
} as const;

export interface TestMetadata {
  // Timing
  time?: number;           // milliseconds
  startTime?: number;      // Unix timestamp
  endTime?: number;        // Unix timestamp
  
  // Status
  skip?: string;           // skip reason
  todo?: string;           // todo reason
  retry?: number;          // retry attempt
  maxRetries?: number;     // max retries allowed
  
  // Error details
  error?: {
    message: string;
    stack?: string;
    diff?: string;
    actual?: any;
    expected?: any;
  };
  
  // Test context
  file?: string;           // source file
  line?: number;           // line number
  column?: number;         // column number
  
  // Custom data
  tags?: string[];         // test tags
  custom?: Record<string, any>;
}

export class ProtocolEncoder {
  /**
   * Encode metadata for inline inclusion
   */
  static encodeInline(type: string, data: any): string {
    if (typeof data === 'string') {
      return `${PROTOCOL.MARKERS.START}${type}:${data}${PROTOCOL.MARKERS.END}`;
    }
    return `${PROTOCOL.MARKERS.START}${type}:${JSON.stringify(data)}${PROTOCOL.MARKERS.END}`;
  }
  
  /**
   * Encode block data for multi-line content
   */
  static encodeBlock(type: string, data: any): string[] {
    const lines: string[] = [];
    lines.push(`${PROTOCOL.MARKERS.START}${type}${PROTOCOL.MARKERS.END}`);
    
    if (typeof data === 'string') {
      lines.push(data);
    } else {
      lines.push(JSON.stringify(data, null, 2));
    }
    
    lines.push(`${PROTOCOL.MARKERS.BLOCK_END}${type}${PROTOCOL.MARKERS.END}`);
    return lines;
  }
  
  /**
   * Create a TAP line with metadata
   */
  static createTestLine(
    status: 'ok' | 'not ok',
    number: number,
    description: string,
    metadata?: TestMetadata
  ): string {
    let line = `${status} ${number} - ${description}`;
    
    if (metadata) {
      // For skip/todo, use inline format for compatibility
      if (metadata.skip) {
        line += ` ${this.encodeInline(PROTOCOL.TYPES.SKIP, metadata.skip)}`;
      } else if (metadata.todo) {
        line += ` ${this.encodeInline(PROTOCOL.TYPES.TODO, metadata.todo)}`;
      } else {
        // For other metadata, append inline
        const metaCopy = { ...metadata };
        delete metaCopy.error; // Error details go in separate block
        
        if (Object.keys(metaCopy).length > 0) {
          line += ` ${this.encodeInline(PROTOCOL.TYPES.META, metaCopy)}`;
        }
      }
    }
    
    return line;
  }
}

export class ProtocolDecoder {
  /**
   * Extract all protocol markers from a line
   */
  static extractMarkers(line: string): Array<{type: string, data: any, start: number, end: number}> {
    const markers: Array<{type: string, data: any, start: number, end: number}> = [];
    let searchFrom = 0;
    
    while (true) {
      const start = line.indexOf(PROTOCOL.MARKERS.START, searchFrom);
      if (start === -1) break;
      
      const end = line.indexOf(PROTOCOL.MARKERS.END, start);
      if (end === -1) break;
      
      const content = line.substring(start + PROTOCOL.MARKERS.START.length, end);
      const colonIndex = content.indexOf(':');
      
      if (colonIndex !== -1) {
        const type = content.substring(0, colonIndex);
        const dataStr = content.substring(colonIndex + 1);
        
        let data: any;
        try {
          // Try to parse as JSON first
          data = JSON.parse(dataStr);
        } catch {
          // If not JSON, treat as string
          data = dataStr;
        }
        
        markers.push({
          type,
          data,
          start,
          end: end + PROTOCOL.MARKERS.END.length
        });
      }
      
      searchFrom = end + 1;
    }
    
    return markers;
  }
  
  /**
   * Remove protocol markers from a line
   */
  static cleanLine(line: string): string {
    const markers = this.extractMarkers(line);
    
    // Remove markers from end to start to preserve indices
    let cleanedLine = line;
    for (let i = markers.length - 1; i >= 0; i--) {
      const marker = markers[i];
      cleanedLine = cleanedLine.substring(0, marker.start) + 
                    cleanedLine.substring(marker.end);
    }
    
    return cleanedLine.trim();
  }
  
  /**
   * Parse a test line and extract metadata
   */
  static parseTestLine(line: string): {
    cleaned: string;
    metadata: TestMetadata;
  } {
    const markers = this.extractMarkers(line);
    const metadata: TestMetadata = {};
    
    for (const marker of markers) {
      switch (marker.type) {
        case PROTOCOL.TYPES.META:
          Object.assign(metadata, marker.data);
          break;
        case PROTOCOL.TYPES.SKIP:
          metadata.skip = marker.data;
          break;
        case PROTOCOL.TYPES.TODO:
          metadata.todo = marker.data;
          break;
      }
    }
    
    return {
      cleaned: this.cleanLine(line),
      metadata
    };
  }
  
  /**
   * Check if a line starts a protocol block
   */
  static isBlockStart(line: string): {isBlock: boolean, type?: string} {
    const trimmed = line.trim();
    if (trimmed.startsWith(PROTOCOL.MARKERS.START) && trimmed.endsWith(PROTOCOL.MARKERS.END)) {
      const content = trimmed.slice(PROTOCOL.MARKERS.START.length, -PROTOCOL.MARKERS.END.length);
      if (!content.includes(':')) {
        return { isBlock: true, type: content };
      }
    }
    return { isBlock: false };
  }
  
  /**
   * Check if a line ends a protocol block
   */
  static isBlockEnd(line: string, type: string): boolean {
    return line.trim() === `${PROTOCOL.MARKERS.BLOCK_END}${type}${PROTOCOL.MARKERS.END}`;
  }
}