import * as path from 'path';
import assert from 'assert';
const IS_WINDOWS = process.platform === 'win32';
/**
 * Similar to path.dirname except normalizes the path separators and slightly better handling for Windows UNC paths.
 *
 * For example, on Linux/macOS:
 * - `/               => /`
 * - `/hello          => /`
 *
 * For example, on Windows:
 * - `C:\             => C:\`
 * - `C:\hello        => C:\`
 * - `C:              => C:`
 * - `C:hello         => C:`
 * - `\               => \`
 * - `\hello          => \`
 * - `\\hello         => \\hello`
 * - `\\hello\world   => \\hello\world`
 */
export function dirname(p) {
    // Normalize slashes and trim unnecessary trailing slash
    p = safeTrimTrailingSeparator(p);
    // Windows UNC root, e.g. \\hello or \\hello\world
    if (IS_WINDOWS && /^\\\\[^\\]+(\\[^\\]+)?$/.test(p)) {
        return p;
    }
    // Get dirname
    let result = path.dirname(p);
    // Trim trailing slash for Windows UNC root, e.g. \\hello\world\
    if (IS_WINDOWS && /^\\\\[^\\]+\\[^\\]+\\$/.test(result)) {
        result = safeTrimTrailingSeparator(result);
    }
    return result;
}
/**
 * Roots the path if not already rooted. On Windows, relative roots like `\`
 * or `C:` are expanded based on the current working directory.
 */
export function ensureAbsoluteRoot(root, itemPath) {
    assert(root, `ensureAbsoluteRoot parameter 'root' must not be empty`);
    assert(itemPath, `ensureAbsoluteRoot parameter 'itemPath' must not be empty`);
    // Already rooted
    if (hasAbsoluteRoot(itemPath)) {
        return itemPath;
    }
    // Windows
    if (IS_WINDOWS) {
        // Check for itemPath like C: or C:foo
        if (itemPath.match(/^[A-Z]:[^\\/]|^[A-Z]:$/i)) {
            let cwd = process.cwd();
            assert(cwd.match(/^[A-Z]:\\/i), `Expected current directory to start with an absolute drive root. Actual '${cwd}'`);
            // Drive letter matches cwd? Expand to cwd
            if (itemPath[0].toUpperCase() === cwd[0].toUpperCase()) {
                // Drive only, e.g. C:
                if (itemPath.length === 2) {
                    // Preserve specified drive letter case (upper or lower)
                    return `${itemPath[0]}:\\${cwd.substr(3)}`;
                }
                // Drive + path, e.g. C:foo
                else {
                    if (!cwd.endsWith('\\')) {
                        cwd += '\\';
                    }
                    // Preserve specified drive letter case (upper or lower)
                    return `${itemPath[0]}:\\${cwd.substr(3)}${itemPath.substr(2)}`;
                }
            }
            // Different drive
            else {
                return `${itemPath[0]}:\\${itemPath.substr(2)}`;
            }
        }
        // Check for itemPath like \ or \foo
        else if (normalizeSeparators(itemPath).match(/^\\$|^\\[^\\]/)) {
            const cwd = process.cwd();
            assert(cwd.match(/^[A-Z]:\\/i), `Expected current directory to start with an absolute drive root. Actual '${cwd}'`);
            return `${cwd[0]}:\\${itemPath.substr(1)}`;
        }
    }
    assert(hasAbsoluteRoot(root), `ensureAbsoluteRoot parameter 'root' must have an absolute root`);
    // Otherwise ensure root ends with a separator
    if (root.endsWith('/') || (IS_WINDOWS && root.endsWith('\\'))) {
        // Intentionally empty
    }
    else {
        // Append separator
        root += path.sep;
    }
    return root + itemPath;
}
/**
 * On Linux/macOS, true if path starts with `/`. On Windows, true for paths like:
 * `\\hello\share` and `C:\hello` (and using alternate separator).
 */
export function hasAbsoluteRoot(itemPath) {
    assert(itemPath, `hasAbsoluteRoot parameter 'itemPath' must not be empty`);
    // Normalize separators
    itemPath = normalizeSeparators(itemPath);
    // Windows
    if (IS_WINDOWS) {
        // E.g. \\hello\share or C:\hello
        return itemPath.startsWith('\\\\') || /^[A-Z]:\\/i.test(itemPath);
    }
    // E.g. /hello
    return itemPath.startsWith('/');
}
/**
 * On Linux/macOS, true if path starts with `/`. On Windows, true for paths like:
 * `\`, `\hello`, `\\hello\share`, `C:`, and `C:\hello` (and using alternate separator).
 */
export function hasRoot(itemPath) {
    assert(itemPath, `isRooted parameter 'itemPath' must not be empty`);
    // Normalize separators
    itemPath = normalizeSeparators(itemPath);
    // Windows
    if (IS_WINDOWS) {
        // E.g. \ or \hello or \\hello
        // E.g. C: or C:\hello
        return itemPath.startsWith('\\') || /^[A-Z]:/i.test(itemPath);
    }
    // E.g. /hello
    return itemPath.startsWith('/');
}
/**
 * Removes redundant slashes and converts `/` to `\` on Windows
 */
export function normalizeSeparators(p) {
    p = p || '';
    // Windows
    if (IS_WINDOWS) {
        // Convert slashes on Windows
        p = p.replace(/\//g, '\\');
        // Remove redundant slashes
        const isUnc = /^\\\\+[^\\]/.test(p); // e.g. \\hello
        return (isUnc ? '\\' : '') + p.replace(/\\\\+/g, '\\'); // preserve leading \\ for UNC
    }
    // Remove redundant slashes
    return p.replace(/\/\/+/g, '/');
}
/**
 * Normalizes the path separators and trims the trailing separator (when safe).
 * For example, `/foo/ => /foo` but `/ => /`
 */
export function safeTrimTrailingSeparator(p) {
    // Short-circuit if empty
    if (!p) {
        return '';
    }
    // Normalize separators
    p = normalizeSeparators(p);
    // No trailing slash
    if (!p.endsWith(path.sep)) {
        return p;
    }
    // Check '/' on Linux/macOS and '\' on Windows
    if (p === path.sep) {
        return p;
    }
    // On Windows check if drive root. E.g. C:\
    if (IS_WINDOWS && /^[A-Z]:\\$/i.test(p)) {
        return p;
    }
    // Otherwise trim trailing slash
    return p.substr(0, p.length - 1);
}
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