/**
 * The map of all source files to their content and compiled value
 */
let COMPILER_fileMap = { }

/**
 * The compiled program
 */
let COMPILER_emitted_value = ''


/**
 * Registers a file with the compiler
 * @param {*} fileName The file's name
 * @param {*} content The content of the file
 */
const COMPILER_registerFile = (fileName, content) => {
    let normalizedFilePath = FILE_RESOLUTION_getFilePath(fileName,false)
    loggerScripts.INFO('REGISTER FILE ' + normalizedFilePath)
    COMPILER_fileMap[normalizedFilePath] = {
        content: content,
        compiled: ts.createSourceFile(
            normalizedFilePath, content, ts.ScriptTarget.Latest
        )
    }
}


/**
 * The callback invoked when the compiler host tries to read a file
 * @param {*} fileName The name of the file
 * @param {*} languageVersion The language version
 * @returns The file if it exists, null otherwise
 */
const COMPILER_getSourceFile = (fileName, languageVersion) => {
    if(!!COMPILER_fileMap[fileName]){
        return COMPILER_fileMap[fileName].compiled
    } else {
        return null
    }
}


/**
 * Constructs the compiler host
 * https://www.typescriptlang.org/tsconfig/#compilerOptions
 */
const COMPILER_customCompilerHost = {
    getSourceFile: COMPILER_getSourceFile,
    writeFile: (fileName, data) => {
        let normalizedFilePath = FILE_RESOLUTION_getFilePath(fileName)
        loggerScripts.INFO("EMIT FILE " + normalizedFilePath)
        let finalData = 
        "let exports = { }\n" +
        data + "\n" +
        "return exports"
        // COMPILER_emitted_value = data
        COMPILER_fileMap[normalizedFilePath] = {
            content: data, //to be eval'd from top level
            moduleContent: finalData, //to be eval'd from require()
        }
    },
    getDefaultLibFileName: () => "lib.d.ts",
    useCaseSensitiveFileNames: () => false,
    getCanonicalFileName: filename => filename,
    getCurrentDirectory: () => "",
    getNewLine: () => "\n",
    getDirectories: () => [],
    fileExists: () => true,
    readFile: () => ""
}

/**
 * Instructs Typescript to emit the final compiled value
 */
const COMPILER_run = () => {
    loggerScripts.INFO('COMPILE ALL REGISTERED FILES')

    const compilerOptions = { }

    const COMPILER_program = ts.createProgram(
        Object.keys(COMPILER_fileMap), compilerOptions, COMPILER_customCompilerHost
    )
    COMPILER_program.emit()
}

/**
 * Loads a file
 * @param {*} fileName The name of the file to load (preferably already has .ts at the end)
 */
const COMPILER_runFile = (fileName) => {
    let normalizedFilePath = FILE_RESOLUTION_getFilePath(fileName)
    if(!!COMPILER_fileMap[normalizedFilePath]){
        loggerScripts.INFO('RUN FILE ' + normalizedFilePath)
        eval(COMPILER_fileMap[normalizedFilePath].content)
    } else {
        const message = 'FAILED TO RESOLVE FILE ' + normalizedFilePath
        loggerScripts.WARNING(message)
        throw new Error(message)
    }
}

/**
 * Loads a file
 * @param {*} fileName The name of the file to load (preferably already has .ts at the end)
 */
const COMPILER_printSource = (fileName) => {
    let normalizedFilePath = FILE_RESOLUTION_getFilePath(fileName)
    if(!!COMPILER_fileMap[normalizedFilePath]){
        loggerScripts.INFO('FILE CONTENT ' + normalizedFilePath)
    } else {
        const message = 'FAILED TO RESOLVE FILE ' + normalizedFilePath
        loggerScripts.WARNING(message)
        loggerScripts.WARNING('file map content:')
        loggerScripts.WARNING(OBject.keys(COMPILER_fileMap) + "")
        throw new Error(message)
    }
}