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450import { readFileSync } from 'fs';
import { EnvVariable, ParsedValue, MultilineStart } from '../types/index.js';
/**
* Environment File Parser
*
* Parses .env files into structured format, handling all edge cases:
* - Comments (# and //)
* - Empty lines
* - Quoted values (single and double quotes)
* - Multi-line values
* - Inline comments
* - Escape sequences
*/
export class EnvFileParser {
/**
* Parse .env file into map of variables
*
* @param filePath - Path to .env file
* @returns Map of key to EnvVariable
*/
parse(filePath: string): Map<string, EnvVariable> {
const content = readFileSync(filePath, 'utf8');
const lines = content.split('\n');
const variables = new Map<string, EnvVariable>();
let multilineBuffer: string | null = null;
let multilineStart = 0;
let multilineKey = '';
for (let i = 0; i < lines.length; i++) {
const line = lines[i];
// Handle multiline continuation
if (multilineBuffer !== null) {
multilineBuffer += '\n' + line;
if (this.isMultilineComplete(multilineBuffer)) {
const variable = this.parseLine(multilineBuffer, multilineStart, multilineKey);
if (variable) {
variables.set(variable.key, variable);
}
multilineBuffer = null;
multilineKey = '';
}
continue;
}
// Skip comments and empty lines
if (this.isComment(line) || line.trim() === '') {
continue;
}
// Check if line starts multiline value
const multilineInfo = this.startsMultiline(line);
if (multilineInfo) {
multilineBuffer = line;
multilineStart = i + 1;
multilineKey = multilineInfo.key;
continue;
}
// Parse single line
const variable = this.parseLine(line, i + 1);
if (variable) {
variables.set(variable.key, variable);
}
}
// Handle unclosed multiline (treat as error, but include what we have)
if (multilineBuffer !== null) {
console.warn(`Warning: Unclosed multiline value for ${multilineKey} at line ${multilineStart}`);
const variable = this.parseLine(multilineBuffer, multilineStart, multilineKey);
if (variable) {
variables.set(variable.key, variable);
}
}
return variables;
}
/**
* Convert variable map back to .env format
*
* @param vars - Map of key to EnvVariable
* @returns Formatted .env file content
*/
stringify(vars: Map<string, EnvVariable>): string {
const lines: string[] = [];
// Sort by line number to maintain order
const sorted = Array.from(vars.values()).sort((a, b) => (a.lineNumber ?? 0) - (b.lineNumber ?? 0));
for (const variable of sorted) {
const { key, value, hasQuotes, quoteType, comment } = variable;
let line = `${key}=`;
if (hasQuotes && quoteType) {
const quote = quoteType === 'single' ? "'" : '"';
line += `${quote}${value}${quote}`;
} else {
line += value;
}
if (comment) {
line += ` ${comment}`;
}
lines.push(line);
}
return lines.join('\n') + '\n';
}
/**
* Parse a single line (or multiline buffer) into EnvVariable
*
* @param line - Line to parse
* @param lineNumber - Line number in file
* @param knownKey - Optional key if already parsed (for multiline)
* @returns EnvVariable or null if invalid
*/
private parseLine(line: string, lineNumber: number, knownKey?: string): EnvVariable | null {
// Remove leading/trailing whitespace
const trimmed = line.trim();
// Skip if empty after trimming
if (trimmed === '') {
return null;
}
// Find first = sign
const equalIndex = trimmed.indexOf('=');
if (equalIndex === -1) {
console.warn(`Warning: Invalid line ${lineNumber}: ${trimmed.substring(0, 50)}`);
return null;
}
// Extract key
const key = knownKey || trimmed.substring(0, equalIndex).trim();
// Validate key (must be alphanumeric + underscore)
if (!this.isValidKey(key)) {
console.warn(`Warning: Invalid key "${key}" at line ${lineNumber}`);
return null;
}
// Extract value part (everything after =)
const valuePart = trimmed.substring(equalIndex + 1);
// Parse value and detect quotes
const valueInfo = this.parseValue(valuePart);
return {
key,
value: valueInfo.value,
lineNumber,
comment: valueInfo.comment,
hasQuotes: valueInfo.hasQuotes,
quoteType: valueInfo.quoteType
};
}
/**
* Parse value part of KEY=VALUE
*
* @param valuePart - String after the = sign
* @returns Parsed value information
*/
private parseValue(valuePart: string): ParsedValue {
const trimmed = valuePart.trim();
// Check for quotes
if (trimmed.startsWith('"') || trimmed.startsWith("'")) {
const quoteChar = trimmed[0];
const quoteType = quoteChar === '"' ? 'double' : 'single';
// Find closing quote
let endIndex = 1;
let escaped = false;
while (endIndex < trimmed.length) {
const char = trimmed[endIndex];
if (escaped) {
escaped = false;
endIndex++;
continue;
}
if (char === '\\') {
escaped = true;
endIndex++;
continue;
}
if (char === quoteChar) {
// Found closing quote
const value = trimmed.substring(1, endIndex);
// Check for inline comment after quote
const afterQuote = trimmed.substring(endIndex + 1).trim();
const comment = this.extractInlineComment(afterQuote);
return {
value: this.unescapeValue(value, quoteType),
hasQuotes: true,
quoteType,
comment
};
}
endIndex++;
}
// No closing quote found (might be multiline)
return {
value: trimmed.substring(1),
hasQuotes: true,
quoteType
};
}
// Unquoted value
// Check for inline comment
const commentIndex = this.findInlineComment(trimmed);
if (commentIndex !== -1) {
const value = trimmed.substring(0, commentIndex).trim();
const comment = trimmed.substring(commentIndex);
return {
value,
hasQuotes: false,
comment
};
}
return {
value: trimmed,
hasQuotes: false
};
}
/**
* Unescape value based on quote type
*
* @param value - Escaped value
* @param quoteType - Type of quotes used
* @returns Unescaped value
*/
private unescapeValue(value: string, quoteType: 'single' | 'double'): string {
if (quoteType === 'single') {
// Single quotes: only escape single quote itself
return value.replace(/\\'/g, "'");
}
// Double quotes: unescape common sequences
return value
.replace(/\\n/g, '\n')
.replace(/\\r/g, '\r')
.replace(/\\t/g, '\t')
.replace(/\\"/g, '"')
.replace(/\\\\/g, '\\');
}
/**
* Find index of inline comment (# or //)
*
* @param line - Line to search
* @returns Index of comment start, or -1 if none
*/
private findInlineComment(line: string): number {
// Look for # or //
const hashIndex = line.indexOf('#');
// For //, require whitespace before it to avoid matching URLs (http://, https://)
// This prevents treating http://example.com as a comment
let slashIndex = -1;
const slashPattern = / \/\//; // Space followed by //
const match = line.match(slashPattern);
if (match && match.index !== undefined) {
slashIndex = match.index + 1; // +1 to skip the space and point to //
}
if (hashIndex === -1 && slashIndex === -1) {
return -1;
}
if (hashIndex === -1) return slashIndex;
if (slashIndex === -1) return hashIndex;
return Math.min(hashIndex, slashIndex);
}
/**
* Extract inline comment from string
*
* @param str - String potentially containing comment
* @returns Comment or undefined
*/
private extractInlineComment(str: string): string | undefined {
if (str.startsWith('#') || str.startsWith('//')) {
return str;
}
return undefined;
}
/**
* Check if line is a comment
*
* @param line - Line to check
* @returns True if comment line
*/
private isComment(line: string): boolean {
const trimmed = line.trim();
return trimmed.startsWith('#') || trimmed.startsWith('//');
}
/**
* Check if line starts a multiline value
*
* @param line - Line to check
* @returns Key if multiline starts, null otherwise
*/
private startsMultiline(line: string): MultilineStart | null {
const equalIndex = line.indexOf('=');
if (equalIndex === -1) return null;
const key = line.substring(0, equalIndex).trim();
const valuePart = line.substring(equalIndex + 1).trim();
// Check if value starts with quote but doesn't end with it
if (valuePart.startsWith('"')) {
// Count unescaped quotes
let quoteCount = 0;
let escaped = false;
for (let i = 0; i < valuePart.length; i++) {
const char = valuePart[i];
if (escaped) {
escaped = false;
continue;
}
if (char === '\\') {
escaped = true;
continue;
}
if (char === '"') {
quoteCount++;
}
}
// Odd number of quotes = multiline
if (quoteCount % 2 === 1) {
return { key };
}
}
if (valuePart.startsWith("'")) {
// Same for single quotes
let quoteCount = 0;
let escaped = false;
for (let i = 0; i < valuePart.length; i++) {
const char = valuePart[i];
if (escaped) {
escaped = false;
continue;
}
if (char === '\\') {
escaped = true;
continue;
}
if (char === "'") {
quoteCount++;
}
}
if (quoteCount % 2 === 1) {
return { key };
}
}
return null;
}
/**
* Check if multiline value is complete
*
* @param buffer - Accumulated multiline buffer
* @returns True if complete
*/
private isMultilineComplete(buffer: string): boolean {
// Find the quote type from first line
const equalIndex = buffer.indexOf('=');
if (equalIndex === -1) return false;
const valuePart = buffer.substring(equalIndex + 1).trim();
const quoteChar = valuePart[0];
if (quoteChar !== '"' && quoteChar !== "'") {
return false;
}
// Count unescaped quotes
let quoteCount = 0;
let escaped = false;
for (let i = 0; i < buffer.length; i++) {
const char = buffer[i];
if (escaped) {
escaped = false;
continue;
}
if (char === '\\') {
escaped = true;
continue;
}
if (char === quoteChar) {
quoteCount++;
}
}
// Even number of quotes = complete
return quoteCount % 2 === 0 && quoteCount > 0;
}
/**
* Validate environment variable key
*
* @param key - Key to validate
* @returns True if valid
*/
private isValidKey(key: string): boolean {
// Must be alphanumeric + underscore, cannot start with number
return /^[A-Za-z_][A-Za-z0-9_]*$/.test(key);
}
}