/**
 * @license
 * Copyright 2025 Google LLC
 * SPDX-License-Identifier: Apache-2.0
 */
import stripAnsi from 'strip-ansi';
/**
 * Safely replaces text with literal strings, avoiding ECMAScript GetSubstitution issues.
 * Escapes $ characters to prevent template interpretation.
 */
export function safeLiteralReplace(str, oldString, newString) {
    if (oldString === '' || !str.includes(oldString)) {
        return str;
    }
    if (!newString.includes('$')) {
        return str.replaceAll(oldString, newString);
    }
    const escapedNewString = newString.replaceAll('$', '$$$$');
    return str.replaceAll(oldString, escapedNewString);
}
/**
 * Strips ANSI/VT escape sequences from a raw byte buffer.
 * Uses latin1 encoding to preserve every byte's value exactly (0-255)
 * while allowing string-based removal of escape sequences.
 */
export function stripAnsiFromBuffer(data) {
    const stripped = stripAnsi(data.toString('latin1'));
    return Buffer.from(stripped, 'latin1');
}
/**
 * Checks if a Buffer is likely binary by testing for the presence of a NULL byte.
 * The presence of a NULL byte is a strong indicator that the data is not plain text.
 * @param data The Buffer to check.
 * @param sampleSize The number of bytes from the start of the buffer to test.
 * @param isPtyOutput When true, ANSI escape sequences are stripped before
 *   checking and a null-byte ratio threshold is used instead of failing on
 *   a single null byte.  This prevents false positives caused by node-pty
 *   on Windows emitting VT control sequences that contain null bytes.
 * @returns True if the data is likely binary, false otherwise.
 */
export function isBinary(data, sampleSize = 512, isPtyOutput = false) {
    if (!data) {
        return false;
    }
    let sample = data.length > sampleSize ? data.subarray(0, sampleSize) : data;
    if (isPtyOutput) {
        sample = stripAnsiFromBuffer(sample);
        if (sample.length === 0) {
            return false;
        }
        let nullCount = 0;
        for (const byte of sample) {
            if (byte === 0) {
                nullCount++;
            }
        }
        return nullCount / sample.length > 0.1;
    }
    for (const byte of sample) {
        // The presence of a NULL byte (0x00) is one of the most reliable
        // indicators of a binary file. Text files should not contain them.
        if (byte === 0) {
            return true;
        }
    }
    // If no NULL bytes were found in the sample, we assume it's text.
    return false;
}
/**
 * Detects the line ending style of a string.
 * @param content The string content to analyze.
 * @returns '\r\n' for Windows-style, '\n' for Unix-style.
 */
export function detectLineEnding(content) {
    // If a Carriage Return is found, assume Windows-style endings.
    // This is a simple but effective heuristic.
    return content.includes('\r\n') ? '\r\n' : '\n';
}
/**
 * Truncates a string to a maximum length, appending a suffix if truncated.
 * @param str The string to truncate.
 * @param maxLength The maximum length of the string.
 * @param suffix The suffix to append if truncated (default: '...[TRUNCATED]').
 * @returns The truncated string.
 */
export function truncateString(str, maxLength, suffix = '...[TRUNCATED]') {
    if (str.length <= maxLength) {
        return str;
    }
    // This regex matches a "Grapheme Cluster" manually:
    // 1. A surrogate pair OR a single character...
    // 2. Followed by any number of "Combining Marks" (\p{M})
    // 'u' flag is required for Unicode property escapes
    const graphemeRegex = /(?:[\uD800-\uDBFF][\uDC00-\uDFFF]|.)\p{M}*/gu;
    let truncatedStr = '';
    let match;
    while ((match = graphemeRegex.exec(str)) !== null) {
        const segment = match[0];
        // If adding the whole cluster (base char + accent) exceeds maxLength, stop.
        if (truncatedStr.length + segment.length > maxLength) {
            break;
        }
        truncatedStr += segment;
        if (truncatedStr.length >= maxLength)
            break;
    }
    // Final safety check for dangling high surrogates
    if (truncatedStr.length > 0) {
        const lastCode = truncatedStr.charCodeAt(truncatedStr.length - 1);
        if (lastCode >= 0xd800 && lastCode <= 0xdbff) {
            truncatedStr = truncatedStr.slice(0, -1);
        }
    }
    return truncatedStr + suffix;
}
/**
 * Safely replaces placeholders in a template string with values from a replacements object.
 * This performs a single-pass replacement to prevent double-interpolation attacks.
 *
 * @param template The template string containing {{key}} placeholders.
 * @param replacements A record of keys to their replacement values.
 * @returns The resulting string with placeholders replaced.
 */
export function safeTemplateReplace(template, replacements) {
    // Regex to match {{key}} in the template string. The regex enforces string naming rules.
    const placeHolderRegex = /\{\{(\w+)\}\}/g;
    return template.replace(placeHolderRegex, (match, key) => Object.prototype.hasOwnProperty.call(replacements, key)
        ? replacements[key]
        : match);
}
/**
 * Sanitizes output for injection into the model conversation.
 * Wraps output in a secure <output> tag and handles potential injection vectors
 * (like closing tags or template patterns) within the data.
 * @param output The raw output to sanitize.
 * @returns The sanitized string ready for injection.
 */
export function sanitizeOutput(output) {
    const trimmed = output.trim();
    if (trimmed.length === 0) {
        return '';
    }
    // Prevent direct closing tag injection.
    const escaped = trimmed.replaceAll('</output>', '&lt;/output&gt;');
    return `<output>\n${escaped}\n</output>`;
}
/**
 * Wraps text in <untrusted_context> tags to mitigate prompt injection.
 */
export function wrapUntrusted(text) {
    const escaped = text.replaceAll('</untrusted_context>', '&lt;/untrusted_context&gt;');
    return `<untrusted_context>\n${escaped}\n</untrusted_context>`;
}
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