const fs = require('fs');
const path = require('path');
const { argv } = require('process');

const config = {
    // replace character of key with value, any character, apart from ['.', '_', '-', ' ']
    'replace': {
        'ä': 'ae',
        'ö': 'oe',
        'ü': 'ue',
        ',': '-',
        '&': 'And',
    },
    'rules': {
        'underscore-before-and-after-number': true, // Will not do trailing or leading for filename
        'enforce-leading-zero': true, // adds a leading zero to any number below 10
        'camel-case-rules': {
            'enforce-snake-case-for-filetypes': ['py'], // using underscores
            'enforce-kebab-case-for-filetypes': ['css', 'html', 'scss', 'tex'], // using hyphens
        },
        'file-start-letter': 'lower', // lower, upper, unchanged
        'directory-start-letter': 'upper', // lower, upper, unchanged
        'replace-dots-with': '', // will not replace as leading character to not break dotfiles
    }
}

/**
 * Recursively find all files with extension in a directory
 * @param {string} dir The directory to search. Either absolute or relative path
 * @param {string} extension The file extension to look for
 * @param {string[]} ignoreList A list of filenames or directories to ignore
 * @returns {{ files: string, directories: string }} returns a list of html files with their full path
 */
const treeWalker = (dir, extension, ignoreList) => {
    const ls = fs.readdirSync(dir);
    const fileList = [];
    const dirList = [];
    for (let file in ls) {
        if (fs.statSync(path.join(dir, ls[file])).isDirectory()) {
            // Filter ignored directories
            if (ignoreList === undefined || !ignoreList.includes(ls[file])) {
                const newData = treeWalker(path.join(dir, ls[file]), extension, ignoreList);
                const newFiles = newData.files;
                dirList.push( path.join( dir, ls[ file ] ) );
                for (let dir = 0; dir < newData.directories.length; dir++) {
                    dirList.push( newData.directories[dir] );
                }
                for (let file = 0; file < newFiles.length; file++) {
                    fileList.push(newFiles[file]);
                }
            }
        } else if (extension == '*' || ls[file].includes(extension)) {
            if (ignoreList === undefined || !ignoreList.includes(ls[file])) {
                fileList.push(path.join(dir, ls[file]));
            }
        }
    }

    return { 'files': fileList, 'directories': dirList };
}

/**
 * @param {string} filename The filename to fix according to the rules
 * @returns {string} the fixed filename
 */
const fixName = ( fn, ft ) => {
    let out = '';
    const enforceSnake = config.rules['camel-case-rules']['enforce-snake-case-for-filetypes'].includes( ft );
    const enforceKebab = config.rules['camel-case-rules']['enforce-kebab-case-for-filetypes'].includes( ft );
    const isDir = ft === 'directory';
    const startLetter = isDir ? config.rules['directory-start-letter'] : config.rules['file-start-letter'];
    let nextUpperCase = false;

    for ( let i = 0; i < fn.length; i++ ) {
        const c = fn[i];
        
        if ( c == '.' ) {
            // Rule: Removed after number, allowed elsewhere
            if ( i > 0 && /[0-9]/.test( fn[ i - 1 ] ) ) {
                out += config.rules[ 'replace-dots-with' ];
            } else {
                out += '.';
            }
        } else if ( /[A-Z]/.test( c ) ) {
            // If we reach a capital letter and enforce either kebab-case or snake_case, we can assume that this is the start of a CamelCase word
            if ( enforceKebab ) {
                out += '-' + c.toLowerCase();
            } else if ( enforceSnake ) {
                out += '_' + c.toLowerCase();
            } else {
                nextUpperCase = false;
                if ( i == 0 && startLetter === 'lower' ) {
                    out += c.toLowerCase();
                } else {
                    out += c;
                }
            }
        } else if ( c == ' ' ) {
            // We always replace spaces, the question is just to what
            if ( enforceKebab ) {
                out += '-';
            } else if ( enforceSnake ) {
                out += '_';
            } else {
                nextUpperCase = true;
            }
        } else if ( c == '_' ) {
            // If we are not enforcing snake_case, then replace it
            if ( !enforceSnake ) {
                if ( needsUnderscore( i, fn ) ) {
                    out += '_';
                } else if ( enforceKebab ) {
                    out += '-';
                } else {
                    nextUpperCase = true;
                }
            } else {
                out += '_'
            }
        } else if ( c == '-' ) {
            // If we are not enforcing kebab-case
            if ( !enforceKebab ) {
                if ( enforceSnake ) {
                    out += '_';
                } else {
                    nextUpperCase = true;
                }
            } else {
                out += '-'
            }
        } else {
            let curr = config.replace[ c ] === undefined ? c : config.replace[ c ];
            if ( config.rules[ 'underscore-before-and-after-number' ] || config.rules['enforce-leading-zero'] ) {
                if ( /[0-9]/.test( c ) ) {
                    if ( i < fn.length - 1 ) {
                        if ( config.rules['enforce-leading-zero'] ) {
                            const prevIsNumber = i > 0 && /[0-9]/.test( fn[i - 1] );
                            const nextIsNumber = /[0-9]/.test( fn[i + 1] );
                            if ( !nextIsNumber && ( i == 0|| !prevIsNumber ) ) {
                                curr = '0' + curr;
                            }
                        }

                        if ( config.rules['underscore-before-and-after-number'] ) {
                            if ( !( /[0-9]/.test( fn[ i + 1 ] ) ) && fn[ i + 1 ] != '_' ) {
                                curr += '_';
                            }
                        }
                    } else {
                        if ( config.rules['enforce-leading-zero'] && ( i > 0 && !( /[0-9]/.test( fn[i - 1] ) ) ) ) {
                            curr = '0' + curr;
                        }
                    }
                } else {
                    if ( config.rules['underscore-before-and-after-number'] && /[0-9]/.test( fn[ i + 1 ] ) ) {
                        curr += '_';
                    }
                }
            }
            if ( nextUpperCase || ( i == 0 && startLetter === 'upper' ) ) {
                nextUpperCase = false;
                out += curr.toUpperCase();
            } else {
                if ( i == 0 && startLetter === 'upper' ) {
                    out += curr.toUpperCase();
                } else {
                    out += curr.toLowerCase();
                }
            }
        }
    }
    return out;
}

const needsUnderscore = ( i, fn ) => {
    return ( i > 0 && /[0-9]/.test( fn[ i - 1 ] ) ) || ( i < fn - 1 && /[0-9]/.test( fn[ i + 1 ] ) )
}

const separateDirAndFileAndFiletype = ( filename ) => {
    const loc = filename.lastIndexOf( '/' ) + 1;
    let ftl = filename.lastIndexOf( '.' ) + 1;
    let fn = filename.substring( loc, ftl - 1 );
    let ft = filename.substring( ftl );
    if ( fs.statSync( filename ).isDirectory() ) {
        ftl = filename.length;
        fn = filename.substring( loc );
        ft = 'directory';
        
    }
    const dir = filename.slice( 0, loc - 1 );
    return { 'filename': fn, 'dir': dir, 'filetype': ft };
}

const fixDirName = ( directory, top ) => {
    if ( directory === top ) {
        return top;
    }

    const f = separateDirAndFileAndFiletype( directory );
    return fixDirName( f.dir, top ) + '/' + fixName( f.filename, f.filetype );
}

if (argv[2] == '-h') {
    console.log('auto-renamer [directory]\n\n=> Recursively rename files in directory');
} else if (argv[2] == '-v') {
    console.log('auto-renamer version 1.0.0, developed by Janis Hutz (development@janishutz.com)');
} else {
    // Recursively add all files in the directory
    const fp = path.resolve( argv[2] );
    const list = treeWalker(fp, '*', ['.git', '@girs']);
    const files = list.files;
    const directories = list.directories;

    for (let i = 0; i < files.length; i++) {
        const file = files[i];
        const f = separateDirAndFileAndFiletype( file );
        let fixedFile = fixName( f.filename, f.filetype );
        
        // Rename
        const fixedPath = f.dir + '/' + fixedFile + '.' + f.filetype;
        console.log( file + ' -> ' + fixedPath );
        fs.renameSync( file, fixedPath );
    }

    // Fix directory names after file names. Sort array by decending length
    directories.sort( ( a, b ) => {
        return b.length - a.length;
    } );

    // separate directories up until we reach the path of dir started in
    for (let i = 0; i < directories.length; i++) {
        const dir = directories[i];
        const fixed = fixDirName( dir, fp );
        console.log( dir + ' -> ' + fixed );
        fs.renameSync( dir, fixDirName( dir, fp ) );
    }
}