const fs = require('fs');
const YAML = require('yaml');
const { NODEVM_SCRIPT_WRAPPER_OFFSET, QUICKJS_SCRIPT_WRAPPER_OFFSET } = require('./sandbox');

const DEFAULT_CONTEXT_LINES = 5;
const ALLOWED_SOURCE_EXTENSIONS = ['.bru', '.yml', '.yaml'];

const isAllowedSourceFile = (filePath) =>
  typeof filePath === 'string' && ALLOWED_SOURCE_EXTENSIONS.some((ext) => filePath.endsWith(ext));

const SCRIPT_TYPES = Object.freeze({
  PRE_REQUEST: 'pre-request',
  POST_RESPONSE: 'post-response',
  TEST: 'test'
});

// Bruno script types → OpenCollection YAML script types
const SCRIPT_TYPE_TO_YML = {
  [SCRIPT_TYPES.PRE_REQUEST]: 'before-request',
  [SCRIPT_TYPES.POST_RESPONSE]: 'after-response',
  [SCRIPT_TYPES.TEST]: 'tests'
};

const readFile = (filePath, cache = null) => {
  if (cache?.has(filePath)) return cache.get(filePath);
  try {
    const content = fs.readFileSync(filePath, 'utf-8').replace(/\r\n/g, '\n');
    if (cache) cache.set(filePath, content);
    return content;
  } catch {
    return null;
  }
};

const BLOCK_PATTERNS = {
  [SCRIPT_TYPES.PRE_REQUEST]: /^script:pre-request\s*\{/,
  [SCRIPT_TYPES.POST_RESPONSE]: /^script:post-response\s*\{/,
  [SCRIPT_TYPES.TEST]: /^tests\s*\{/
};

/** Find the 1-indexed line where a script block's content starts in a .bru file */
const findScriptBlockStartLine = (filePath, scriptType, cache = null) => {
  if (!filePath.endsWith('.bru')) return null;

  const cacheKey = `bru:${filePath}:${scriptType}`;
  if (cache?.has(cacheKey)) return cache.get(cacheKey);

  const content = readFile(filePath, cache);
  if (!content) return null;

  const pattern = BLOCK_PATTERNS[scriptType];
  if (!pattern) return null;

  const lines = content.split('\n');
  let result = null;
  for (let i = 0; i < lines.length; i++) {
    if (pattern.test(lines[i])) {
      result = i + 2; // +1 for 1-indexing, +1 for line after opening brace
      break;
    }
  }

  if (cache) cache.set(cacheKey, result);
  return result;
};

/** Find the 1-indexed line where a script block's content starts in a .yml file */
const findYmlScriptBlockStartLine = (filePath, scriptType, cache = null) => {
  if (!filePath.endsWith('.yml') && !filePath.endsWith('.yaml')) return null;

  const cacheKey = `yml:${filePath}:${scriptType}`;
  if (cache?.has(cacheKey)) return cache.get(cacheKey);

  const content = readFile(filePath, cache);
  if (!content) return null;

  const ymlType = SCRIPT_TYPE_TO_YML[scriptType];
  if (!ymlType) return null;

  let result = null;
  try {
    const lineCounter = new YAML.LineCounter();
    const doc = YAML.parseDocument(content, { lineCounter });

    // Request yml files use runtime.scripts, collection/folder yml files use request.scripts
    const scriptPaths = [['runtime', 'scripts'], ['request', 'scripts']];
    for (const scriptPath of scriptPaths) {
      const scripts = doc.getIn(scriptPath, true);
      if (YAML.isSeq(scripts)) {
        for (const item of scripts.items) {
          if (!YAML.isMap(item)) continue;
          if (item.get('type') === ymlType) {
            const codeNode = item.get('code', true);
            if (codeNode && codeNode.range) {
              result = lineCounter.linePos(codeNode.range[0]).line + 1;
              break;
            }
          }
        }
        if (result) break;
      }
    }
  } catch {
    // invalid YAML
  }

  if (cache) cache.set(cacheKey, result);
  return result;
};

/** Adjust a runtime-reported line number to the actual line in the .bru/.yml file */
const adjustLineNumber = (filePath, reportedLine, isQuickJS, scriptType = null, cache = null, scriptMetadata = null) => {
  const isBruFile = filePath.endsWith('.bru');
  const isYmlFile = filePath.endsWith('.yml') || filePath.endsWith('.yaml');

  if (!isBruFile && !isYmlFile) {
    return reportedLine;
  }

  const wrapperOffset = isQuickJS ? QUICKJS_SCRIPT_WRAPPER_OFFSET : NODEVM_SCRIPT_WRAPPER_OFFSET;
  const scriptRelativeLine = reportedLine - wrapperOffset;

  if (scriptRelativeLine < 1) return reportedLine;

  // Use metadata if available to correctly map line numbers in combined scripts
  if (scriptType && scriptMetadata) {
    const { requestStartLine, requestEndLine } = scriptMetadata;
    if (requestStartLine != null && requestEndLine != null) {
      if (scriptRelativeLine >= requestStartLine && scriptRelativeLine <= requestEndLine) {
        // Error is within the request script segment
        const blockStartLine = isBruFile
          ? findScriptBlockStartLine(filePath, scriptType, cache)
          : findYmlScriptBlockStartLine(filePath, scriptType, cache);

        if (blockStartLine) {
          return blockStartLine + (scriptRelativeLine - requestStartLine) - 1;
        }
      } else {
        // Error is in a collection/folder-level script
        // Cannot map to the request .bru/.yml file, return null to skip source context.
        return null;
      }
    }
  }

  // No segment metadata, map script-relative line to file line via block start.
  if (scriptType) {
    const blockStartLine = isBruFile
      ? findScriptBlockStartLine(filePath, scriptType, cache)
      : findYmlScriptBlockStartLine(filePath, scriptType, cache);

    if (blockStartLine) {
      return blockStartLine + scriptRelativeLine - 1;
    }
  }

  return scriptRelativeLine;
};

/**
 * Resolve an error in a collection/folder script segment to its source file and line.
 * Uses the segments array in metadata to find which segment the error falls in,
 * then maps to the actual line in that segment's source file.
 */
const resolveSegmentError = (parsed, metadata, scriptType, cache) => {
  if (!metadata?.segments?.length || !parsed) return null;

  const wrapperOffset = parsed.isQuickJS ? QUICKJS_SCRIPT_WRAPPER_OFFSET : NODEVM_SCRIPT_WRAPPER_OFFSET;
  const scriptRelativeLine = parsed.line - wrapperOffset;
  if (scriptRelativeLine < 1) return null;

  for (const segment of metadata.segments) {
    if (scriptRelativeLine >= segment.startLine && scriptRelativeLine <= segment.endLine) {
      const isBru = segment.filePath.endsWith('.bru');
      const isYml = segment.filePath.endsWith('.yml') || segment.filePath.endsWith('.yaml');
      if (!isBru && !isYml) return null;

      const blockStartLine = isBru
        ? findScriptBlockStartLine(segment.filePath, scriptType, cache)
        : findYmlScriptBlockStartLine(segment.filePath, scriptType, cache);
      if (!blockStartLine) return null;

      return {
        line: blockStartLine + (scriptRelativeLine - segment.startLine) - 1,
        filePath: segment.filePath,
        displayPath: segment.displayPath
      };
    }
  }
  return null;
};

/** Extract file path, line, column, and runtime type from a single stack trace line */
const matchStackFrame = (line) => {
  // QuickJS: "at (/path/to/file.bru:11)" or "at <anonymous> (/path/to/file.bru:11)"
  const quickjsMatch = line.match(/at (?:<[^>]+>\s*)?\(((?:[A-Za-z]:)?[^:]+):(\d+)(?::(\d+))?\)/);
  if (quickjsMatch && (quickjsMatch[1].includes('/') || quickjsMatch[1].includes('\\'))) {
    return {
      filePath: quickjsMatch[1],
      line: parseInt(quickjsMatch[2], 10),
      column: quickjsMatch[3] ? parseInt(quickjsMatch[3], 10) : null,
      isQuickJS: true
    };
  }

  // Node VM: "at /path/to/file.bru:11:5" or "at Object.<anonymous> (/path/to/file.bru:11:5)"
  const nodeMatch = line.match(/at (?:.*?\()?((?:[A-Za-z]:)?[^:]+):(\d+)(?::(\d+))?\)?/);
  if (nodeMatch && (nodeMatch[1].includes('/') || nodeMatch[1].includes('\\'))) {
    return {
      filePath: nodeMatch[1],
      line: parseInt(nodeMatch[2], 10),
      column: nodeMatch[3] ? parseInt(nodeMatch[3], 10) : null,
      isQuickJS: false
    };
  }

  return null;
};

/** Parse the first stack frame to extract file path, line, and column */
const parseStackTrace = (stack) => {
  if (!stack) return null;

  for (const line of stack.split('\n')) {
    const match = matchStackFrame(line);
    if (match) return match;
  }

  return null;
};

const parseErrorLocation = (error) => {
  if (error.__callSites?.length > 0) {
    const first = error.__callSites[0];
    return {
      filePath: first.filePath,
      line: first.line,
      column: first.column,
      isQuickJS: false
    };
  }

  /* falls back to string parsing */
  const parsed = parseStackTrace(error.stack);
  if (parsed && error.__isQuickJS) {
    parsed.isQuickJS = true;
  }
  return parsed;
};

/** Read source file and extract context lines around the error location */
const getSourceContext = (filePath, errorLine, contextLines = DEFAULT_CONTEXT_LINES, cache = null) => {
  const content = readFile(filePath, cache);
  if (!content) return null;

  const lines = content.split('\n');
  const startLine = Math.max(1, errorLine - contextLines);
  const endLine = Math.min(lines.length, errorLine + contextLines);

  const contextLinesArray = [];
  for (let i = startLine; i <= endLine; i++) {
    contextLinesArray.push({
      lineNumber: i,
      content: lines[i - 1],
      isError: i === errorLine
    });
  }

  return { lines: contextLinesArray, startLine, errorLine };
};

/** Build adjusted stack trace string from structured CallSite data */
const buildStackFromCallSites = (callSites, scriptType = null, cache = null, scriptMetadata = null) => {
  return callSites.map((site) => {
    const adjusted = adjustLineNumber(site.filePath, site.line, false, scriptType, cache, scriptMetadata);
    let fileToUse = site.filePath;
    let lineToUse = adjusted !== null ? adjusted : site.line;

    // Try segment resolution for collection/folder frames
    if (adjusted === null && scriptMetadata?.segments) {
      const parsed = { line: site.line, isQuickJS: false };
      const resolved = resolveSegmentError(parsed, scriptMetadata, scriptType, cache);
      if (resolved) {
        fileToUse = resolved.filePath;
        lineToUse = resolved.line;
      }
    }

    const loc = site.column ? `${fileToUse}:${lineToUse}:${site.column}` : `${fileToUse}:${lineToUse}`;
    const name = site.functionName ? `${site.functionName} (${loc})` : loc;
    return `    at ${name}`;
  }).join('\n');
};

/** Adjust all line numbers in a stack trace string */
const adjustStackTrace = (stack, scriptType = null, cache = null, scriptMetadata = null, forceQuickJS = false) => {
  if (!stack) return stack;

  return stack.split('\n').map((line) => {
    const match = matchStackFrame(line);
    if (!match) return line;

    const isQuickJS = forceQuickJS || match.isQuickJS;
    const adjusted = adjustLineNumber(match.filePath, match.line, isQuickJS, scriptType, cache, scriptMetadata);

    // Try segment resolution for collection/folder frames
    if (adjusted === null && scriptMetadata?.segments) {
      const parsed = { line: match.line, isQuickJS };
      const resolved = resolveSegmentError(parsed, scriptMetadata, scriptType, cache);
      if (resolved) {
        const suffix = match.isQuickJS ? ')' : '';
        return match.column !== null
          ? line.replace(`${match.filePath}:${match.line}:${match.column}${suffix}`, `${resolved.filePath}:${resolved.line}:${match.column}${suffix}`)
          : line.replace(`${match.filePath}:${match.line}${suffix}`, `${resolved.filePath}:${resolved.line}${suffix}`);
      }
      return line;
    }

    if (adjusted === null || adjusted === match.line) return line;

    const suffix = match.isQuickJS ? ')' : '';
    return match.column !== null
      ? line.replace(`:${match.line}:${match.column}${suffix}`, `:${adjusted}:${match.column}${suffix}`)
      : line.replace(`:${match.line}${suffix}`, `:${adjusted}${suffix}`);
  }).join('\n');
};

/** Resolve original error name from wrapped errors (QuickJS cause / Node VM ScriptError) */
const getErrorTypeName = (error) => {
  return error.cause?.name || error.originalError?.name || error.name || error.constructor?.name || 'Error';
};

/** Format an error with source context and adjusted line numbers */
const formatErrorWithContext = (error, relativeFilePath = null, scriptType = null, contextLines = DEFAULT_CONTEXT_LINES, scriptMetadata = null) => {
  if (!error) return '';

  const cache = new Map();
  // Use metadata from error object if available, otherwise use passed parameter
  const metadata = error.scriptMetadata || scriptMetadata;

  const parsed = parseErrorLocation(error);
  if (!parsed) {
    return `${error.message}\n${error.stack || ''}`;
  }

  const { filePath } = parsed;
  const adjustedLine = adjustLineNumber(filePath, parsed.line, parsed.isQuickJS, scriptType, cache, metadata);

  // adjustedLine === null means the error is in a collection/folder script
  // resolve to the collection/folder source file using segment metadata
  let segmentResult = null;
  if (adjustedLine === null) {
    segmentResult = resolveSegmentError(parsed, metadata, scriptType, cache);
    if (!segmentResult) {
      // Fallback: no segment resolution possible, show message + stack only
      const errorType = getErrorTypeName(error);
      const parts = [`${errorType}: ${error.message}`];
      if (error.__callSites?.length > 0) {
        parts.push(buildStackFromCallSites(error.__callSites, scriptType, cache, metadata));
      } else if (error.stack) {
        const stackLines = error.stack.split('\n').slice(1);
        for (const stackLine of stackLines) {
          parts.push(`    ${stackLine.trim()}`);
        }
      }
      return parts.join('\n');
    }
  }

  const sourceFile = segmentResult ? segmentResult.filePath : filePath;
  const sourceLine = segmentResult ? segmentResult.line : adjustedLine;
  const context = isAllowedSourceFile(sourceFile) ? getSourceContext(sourceFile, sourceLine, contextLines, cache) : null;

  if (!context) {
    return `${error.message}\n${error.stack || ''}`;
  }

  const displayPath = segmentResult ? segmentResult.displayPath : (relativeFilePath || filePath);
  const lines = [];

  lines.push(`File: ${displayPath}`);
  lines.push('');

  const maxLineNumber = context.lines[context.lines.length - 1].lineNumber;
  const lineNumberWidth = String(maxLineNumber).length;

  for (const lineInfo of context.lines) {
    const lineNum = String(lineInfo.lineNumber).padStart(lineNumberWidth, ' ');
    const prefix = lineInfo.isError ? '>' : ' ';

    lines.push(`${prefix} ${lineNum} |  ${lineInfo.content}`);
  }

  lines.push('');

  const errorType = getErrorTypeName(error);
  lines.push(`${errorType}: ${error.message}`);

  if (error.__callSites?.length > 0) {
    lines.push(buildStackFromCallSites(error.__callSites, scriptType, cache, metadata));
  } else {
    const stackToDisplay = adjustStackTrace(error.stack, scriptType, cache, metadata, parsed.isQuickJS);
    const userStackLines = stackToDisplay.split('\n').slice(1);
    for (const stackLine of userStackLines) {
      lines.push(`    ${stackLine.trim()}`);
    }
  }

  return lines.join('\n');
};

module.exports = {
  SCRIPT_TYPES,
  DEFAULT_CONTEXT_LINES,
  parseStackTrace,
  parseErrorLocation,
  buildStackFromCallSites,
  getSourceContext,
  formatErrorWithContext,
  adjustLineNumber,
  resolveSegmentError,
  findScriptBlockStartLine,
  findYmlScriptBlockStartLine,
  adjustStackTrace,
  getErrorTypeName
};