const fs = require("fs");
const path = require("path");
const { set: lodashset, get: lodashget } = require("@11ty/lodash-custom");
const { TemplatePath, isPlainObject } = require("@11ty/eleventy-utils");

const merge = require("./Util/Merge");
const unique = require("./Util/Unique");
const TemplateGlob = require("./TemplateGlob");
const EleventyExtensionMap = require("./EleventyExtensionMap");
const EleventyBaseError = require("./EleventyBaseError");
const TemplateDataInitialGlobalData = require("./TemplateDataInitialGlobalData");
const { EleventyRequire } = require("./Util/Require");

const debugWarn = require("debug")("Eleventy:Warnings");
const debug = require("debug")("Eleventy:TemplateData");
const debugDev = require("debug")("Dev:Eleventy:TemplateData");

class FSExistsCache {
  constructor() {
    this._cache = new Map();
  }
  has(path) {
    return this._cache.has(path);
  }
  exists(path) {
    let exists = this._cache.get(path);
    if (!this.has(path)) {
      exists = fs.existsSync(path);
      this._cache.set(path, exists);
    }
    return exists;
  }
  markExists(path, value = true) {
    this._cache.set(path, !!value);
  }
}

class TemplateDataConfigError extends EleventyBaseError {}
class TemplateDataParseError extends EleventyBaseError {}

class TemplateData {
  constructor(inputDir, eleventyConfig) {
    if (!eleventyConfig) {
      throw new TemplateDataConfigError("Missing `config`.");
    }
    this.eleventyConfig = eleventyConfig;
    this.config = this.eleventyConfig.getConfig();
    this.benchmarks = {
      data: this.config.benchmarkManager.get("Data"),
      aggregate: this.config.benchmarkManager.get("Aggregate"),
    };

    this.inputDirNeedsCheck = false;
    this.setInputDir(inputDir);

    this.rawImports = {};
    this.globalData = null;
    this.templateDirectoryData = {};

    // It's common for data files not to exist, so we avoid going to the FS to
    // re-check if they do via a quick-and-dirty cache.
    this._fsExistsCache = new FSExistsCache();

    this.initialGlobalData = new TemplateDataInitialGlobalData(this.eleventyConfig);
  }

  setFileSystemSearch(fileSystemSearch) {
    this.fileSystemSearch = fileSystemSearch;
  }

  get extensionMap() {
    if (!this._extensionMap) {
      this._extensionMap = new EleventyExtensionMap([], this.eleventyConfig);
    }
    return this._extensionMap;
  }

  set extensionMap(map) {
    this._extensionMap = map;
  }

  get environmentVariables() {
    return this._env;
  }

  set environmentVariables(env) {
    this._env = env;
  }

  /* Used by tests */
  _setConfig(config) {
    this.config = config;
  }

  setInputDir(inputDir) {
    this.inputDirNeedsCheck = true;
    this.inputDir = inputDir;
    this.dataDir = this.config.dir.data
      ? TemplatePath.join(inputDir, this.config.dir.data)
      : inputDir;
  }

  getRawImports() {
    let pkgPath = TemplatePath.absolutePath("package.json");

    try {
      this.rawImports[this.config.keys.package] = require(pkgPath);
    } catch (e) {
      debug("Could not find and/or require package.json for data preprocessing at %o", pkgPath);
    }

    return this.rawImports;
  }

  getDataDir() {
    return this.dataDir;
  }

  clearData() {
    this.globalData = null;
    this.configApiGlobalData = null;
    this.templateDirectoryData = {};
  }

  _getGlobalDataGlobByExtension(dir, extension) {
    return TemplateGlob.normalizePath(
      dir,
      "/",
      this.config.dir.data !== "." ? this.config.dir.data : "",
      `/**/*.${extension}`
    );
  }

  async _checkInputDir() {
    if (this.inputDirNeedsCheck) {
      let globalPathStat = await fs.promises.stat(this.inputDir);

      if (!globalPathStat.isDirectory()) {
        throw new Error("Could not find data path directory: " + this.inputDir);
      }

      this.inputDirNeedsCheck = false;
    }
  }

  async getInputDir() {
    let dir = ".";

    if (this.inputDir) {
      await this._checkInputDir();
      dir = this.inputDir;
    }

    return dir;
  }

  // This is a backwards compatibility helper with the old `jsDataFileSuffix` configuration API
  getDataFileSuffixes() {
    // New API
    if (Array.isArray(this.config.dataFileSuffixes)) {
      return this.config.dataFileSuffixes;
    }

    // Backwards compatibility
    if (this.config.jsDataFileSuffix) {
      let suffixes = [];
      suffixes.push(this.config.jsDataFileSuffix); // e.g. filename.11tydata.json
      suffixes.push(""); // suffix-less for free with old API, e.g. filename.json
      return suffixes;
    }
    return []; // if both of these entries are set to false, use no files
  }

  // This is used exclusively for --watch and --serve chokidar targets
  async getTemplateDataFileGlob() {
    let suffixes = this.getDataFileSuffixes();
    let globSuffixesWithLeadingDot = new Set();
    globSuffixesWithLeadingDot.add("json"); // covers .11tydata.json too
    let globSuffixesWithoutLeadingDot = new Set();

    // Typically using [ '.11tydata', '' ] suffixes to find data files
    for (let suffix of suffixes) {
      // TODO the `suffix` truthiness check is purely for backwards compat?
      if (suffix && typeof suffix === "string") {
        if (suffix.startsWith(".")) {
          // .suffix.js
          globSuffixesWithLeadingDot.add(`${suffix.slice(1)}.cjs`);
          globSuffixesWithLeadingDot.add(`${suffix.slice(1)}.js`);
        } else {
          // "suffix.js" without leading dot
          globSuffixesWithoutLeadingDot.add(`${suffix || ""}.cjs`);
          globSuffixesWithoutLeadingDot.add(`${suffix || ""}.js`);
        }
      }
    }

    // Configuration Data Extensions e.g. yaml
    if (this.hasUserDataExtensions()) {
      for (let extension of this.getUserDataExtensions()) {
        globSuffixesWithLeadingDot.add(extension); // covers .11tydata.{extension} too
      }
    }

    let dir = await this.getInputDir();
    let paths = [];
    if (globSuffixesWithLeadingDot.size > 0) {
      paths.push(`${dir}/**/*.{${Array.from(globSuffixesWithLeadingDot).join(",")}}`);
    }
    if (globSuffixesWithoutLeadingDot.size > 0) {
      paths.push(`${dir}/**/*{${Array.from(globSuffixesWithoutLeadingDot).join(",")}}`);
    }

    return TemplatePath.addLeadingDotSlashArray(paths);
  }

  // For spidering dependencies
  // TODO Can we reuse getTemplateDataFileGlob instead? Maybe just filter off the .json files before scanning for dependencies
  async getTemplateJavaScriptDataFileGlob() {
    let dir = await this.getInputDir();

    let paths = [];
    let suffixes = this.getDataFileSuffixes();
    for (let suffix of suffixes) {
      if (suffix) {
        // TODO this check is purely for backwards compat and I kinda feel like it shouldn’t be here
        // paths.push(`${dir}/**/*${suffix || ""}.cjs`); // Same as above
        paths.push(`${dir}/**/*${suffix || ""}.js`);
      }
    }

    return TemplatePath.addLeadingDotSlashArray(paths);
  }

  async getGlobalDataGlob() {
    let dir = await this.getInputDir();

    let extGlob = this.getGlobalDataExtensionPriorities().join(",");
    return [this._getGlobalDataGlobByExtension(dir, "{" + extGlob + "}")];
  }

  getWatchPathCache() {
    return this.pathCache;
  }

  getGlobalDataExtensionPriorities() {
    return this.getUserDataExtensions().concat(["json", "cjs", "js"]);
  }

  static calculateExtensionPriority(path, priorities) {
    for (let i = 0; i < priorities.length; i++) {
      let ext = priorities[i];
      if (path.endsWith(ext)) {
        return i;
      }
    }
    return priorities.length;
  }

  async getGlobalDataFiles() {
    let priorities = this.getGlobalDataExtensionPriorities();

    let fsBench = this.benchmarks.aggregate.get("Searching the file system (data)");
    fsBench.before();
    let globs = await this.getGlobalDataGlob();
    let paths = await this.fileSystemSearch.search("global-data", globs);
    fsBench.after();

    // sort paths according to extension priorities
    // here we use reverse ordering, because paths with bigger index in array will override the first ones
    // example [path/file.json, path/file.js] here js will override json
    paths = paths.sort((first, second) => {
      let p1 = TemplateData.calculateExtensionPriority(first, priorities);
      let p2 = TemplateData.calculateExtensionPriority(second, priorities);
      if (p1 < p2) {
        return -1;
      }
      if (p1 > p2) {
        return 1;
      }
      return 0;
    });

    this.pathCache = paths;
    return paths;
  }

  getObjectPathForDataFile(dataFilePath) {
    let reducedPath = TemplatePath.stripLeadingSubPath(dataFilePath, this.dataDir);
    let parsed = path.parse(reducedPath);
    let folders = parsed.dir ? parsed.dir.split("/") : [];
    folders.push(parsed.name);

    return folders;
  }

  async getAllGlobalData() {
    let rawImports = this.getRawImports();
    let globalData = {};
    let files = TemplatePath.addLeadingDotSlashArray(await this.getGlobalDataFiles());

    this.config.events.emit("eleventy.globalDataFiles", files);

    let dataFileConflicts = {};

    for (let j = 0, k = files.length; j < k; j++) {
      let data = await this.getDataValue(files[j], rawImports);
      let objectPathTarget = this.getObjectPathForDataFile(files[j]);

      // Since we're joining directory paths and an array is not useable as an objectkey since two identical arrays are not double equal,
      // we can just join the array by a forbidden character ("/"" is chosen here, since it works on Linux, Mac and Windows).
      // If at some point this isn't enough anymore, it would be possible to just use JSON.stringify(objectPathTarget) since that
      // is guaranteed to work but is signifivcantly slower.
      let objectPathTargetString = objectPathTarget.join(path.sep);

      // if two global files have the same path (but different extensions)
      // and conflict, let’s merge them.
      if (dataFileConflicts[objectPathTargetString]) {
        debugWarn(
          `merging global data from ${files[j]} with an already existing global data file (${dataFileConflicts[objectPathTargetString]}). Overriding existing keys.`
        );

        let oldData = lodashget(globalData, objectPathTarget);
        data = TemplateData.mergeDeep(this.config, oldData, data);
      }

      dataFileConflicts[objectPathTargetString] = files[j];
      debug(`Found global data file ${files[j]} and adding as: ${objectPathTarget}`);
      lodashset(globalData, objectPathTarget, data);
    }

    return globalData;
  }

  async getInitialGlobalData() {
    if (!this.configApiGlobalData) {
      this.configApiGlobalData = new Promise(async (resolve) => {
        let globalData = await this.initialGlobalData.getData();

        if (this.environmentVariables) {
          if (!("env" in globalData.eleventy)) {
            globalData.eleventy.env = {};
          }
          Object.assign(globalData.eleventy.env, this.environmentVariables);
        }

        resolve(globalData);
      });
    }

    return this.configApiGlobalData;
  }

  async getGlobalData() {
    let rawImports = this.getRawImports();

    if (!this.globalData) {
      this.globalData = new Promise(async (resolve) => {
        let configApiGlobalData = await this.getInitialGlobalData();

        let globalJson = await this.getAllGlobalData();
        let mergedGlobalData = merge(globalJson, configApiGlobalData);

        // OK: Shallow merge when combining rawImports (pkg) with global data files
        resolve(Object.assign({}, mergedGlobalData, rawImports));
      });
    }

    return this.globalData;
  }

  /* Template and Directory data files */
  async combineLocalData(localDataPaths) {
    let localData = {};
    if (!Array.isArray(localDataPaths)) {
      localDataPaths = [localDataPaths];
    }

    // Filter out files we know don't exist to avoid overhead for checking
    localDataPaths = localDataPaths.filter((path) => {
      return this._fsExistsCache.exists(path);
    });

    this.config.events.emit("eleventy.dataFiles", localDataPaths);

    if (!localDataPaths.length) {
      return localData;
    }

    let dataSource = {};
    for (let path of localDataPaths) {
      let dataForPath = await this.getDataValue(path, null, true);
      if (!isPlainObject(dataForPath)) {
        debug(
          "Warning: Template and Directory data files expect an object to be returned, instead `%o` returned `%o`",
          path,
          dataForPath
        );
      } else {
        // clean up data for template/directory data files only.
        let cleanedDataForPath = TemplateData.cleanupData(dataForPath);
        for (let key in cleanedDataForPath) {
          if (dataSource.hasOwnProperty(key)) {
            debugWarn(
              "Local data files have conflicting data. Overwriting '%s' with data from '%s'. Previous data location was from '%s'",
              key,
              path,
              dataSource[key]
            );
          }
          dataSource[key] = path;
        }
        TemplateData.mergeDeep(this.config, localData, cleanedDataForPath);
      }
    }
    return localData;
  }

  async getTemplateDirectoryData(templatePath) {
    if (!this.templateDirectoryData[templatePath]) {
      let localDataPaths = await this.getLocalDataPaths(templatePath);
      let importedData = await this.combineLocalData(localDataPaths);

      this.templateDirectoryData[templatePath] = Object.assign({}, importedData);
    }
    return this.templateDirectoryData[templatePath];
  }

  getUserDataExtensions() {
    if (!this.config.dataExtensions) {
      return [];
    }

    // returning extensions in reverse order to create proper extension order
    // later added formats will override first ones
    return Array.from(this.config.dataExtensions.keys()).reverse();
  }

  getUserDataParser(extension) {
    return this.config.dataExtensions.get(extension);
  }

  isUserDataExtension(extension) {
    return this.config.dataExtensions && this.config.dataExtensions.has(extension);
  }

  hasUserDataExtensions() {
    return this.config.dataExtensions && this.config.dataExtensions.size > 0;
  }

  async _loadFileContents(path, options = {}) {
    let rawInput;
    let encoding = "utf8";
    if ("encoding" in options) {
      encoding = options.encoding;
    }

    try {
      rawInput = await fs.promises.readFile(path, encoding);
    } catch (e) {
      // if file does not exist, return nothing
    }

    // Can return a buffer, string, etc
    if (typeof rawInput === "string") {
      return rawInput.trim();
    }

    return rawInput;
  }

  async _parseDataFile(path, rawImports, ignoreProcessing, parser, options = {}) {
    let readFile = !("read" in options) || options.read === true;
    let rawInput;

    if (readFile) {
      rawInput = await this._loadFileContents(path, options);
    }

    if (readFile && !rawInput) {
      return {};
    }

    try {
      if (readFile) {
        return parser(rawInput, path);
      } else {
        // path as a first argument is when `read: false`
        // path as a second argument is for consistency with `read: true` API
        return parser(path, path);
      }
    } catch (e) {
      throw new TemplateDataParseError(`Having trouble parsing data file ${path}`, e);
    }
  }

  // ignoreProcessing = false for global data files
  // ignoreProcessing = true for local data files
  async getDataValue(path, rawImports, ignoreProcessing) {
    let extension = TemplatePath.getExtension(path);

    if (extension === "js" || extension === "cjs") {
      // JS data file or require’d JSON (no preprocessing needed)
      let localPath = TemplatePath.absolutePath(path);
      let exists = this._fsExistsCache.exists(localPath);
      // Make sure that relative lookups benefit from cache
      this._fsExistsCache.markExists(path, exists);

      if (!exists) {
        return {};
      }

      let aggregateDataBench = this.benchmarks.aggregate.get("Data File");
      aggregateDataBench.before();
      let dataBench = this.benchmarks.data.get(`\`${path}\``);
      dataBench.before();

      let returnValue = EleventyRequire(localPath);
      // TODO special exception for Global data `permalink.js`
      // module.exports = (data) => `${data.page.filePathStem}/`; // Does not work
      // module.exports = () => ((data) => `${data.page.filePathStem}/`); // Works
      if (typeof returnValue === "function") {
        let configApiGlobalData = await this.getInitialGlobalData();
        returnValue = await returnValue(configApiGlobalData || {});
      }

      dataBench.after();
      aggregateDataBench.after();
      return returnValue;
    } else if (this.isUserDataExtension(extension)) {
      // Other extensions
      let { parser, options } = this.getUserDataParser(extension);

      return this._parseDataFile(path, rawImports, ignoreProcessing, parser, options);
    } else if (extension === "json") {
      // File to string, parse with JSON (preprocess)
      const parser = (content) => JSON.parse(content);
      return this._parseDataFile(path, rawImports, ignoreProcessing, parser);
    } else {
      throw new TemplateDataParseError(
        `Could not find an appropriate data parser for ${path}. Do you need to add a plugin to your config file?`
      );
    }
  }

  _pushExtensionsToPaths(paths, curpath, extensions) {
    for (let extension of extensions) {
      paths.push(curpath + "." + extension);
    }
  }

  _addBaseToPaths(paths, base, extensions, nonEmptySuffixesOnly = false) {
    let suffixes = this.getDataFileSuffixes();

    for (let suffix of suffixes) {
      suffix = suffix || "";

      if (nonEmptySuffixesOnly && suffix === "") {
        continue;
      }

      // data suffix
      if (suffix) {
        paths.push(base + suffix + ".js");
        paths.push(base + suffix + ".cjs");
      }
      paths.push(base + suffix + ".json"); // default: .11tydata.json

      // inject user extensions
      this._pushExtensionsToPaths(paths, base + suffix, extensions);
    }
  }

  async getLocalDataPaths(templatePath) {
    let paths = [];
    let parsed = path.parse(templatePath);
    let inputDir = TemplatePath.addLeadingDotSlash(TemplatePath.normalize(this.inputDir));

    debugDev("getLocalDataPaths(%o)", templatePath);
    debugDev("parsed.dir: %o", parsed.dir);

    let userExtensions = this.getUserDataExtensions();

    if (parsed.dir) {
      let fileNameNoExt = this.extensionMap.removeTemplateExtension(parsed.base);

      // default dataSuffix: .11tydata, is appended in _addBaseToPaths
      debug("Using %o suffixes to find data files.", this.getDataFileSuffixes());

      // Template data file paths
      let filePathNoExt = parsed.dir + "/" + fileNameNoExt;
      this._addBaseToPaths(paths, filePathNoExt, userExtensions);

      // Directory data file paths
      let allDirs = TemplatePath.getAllDirs(parsed.dir);

      debugDev("allDirs: %o", allDirs);
      for (let dir of allDirs) {
        let lastDir = TemplatePath.getLastPathSegment(dir);
        let dirPathNoExt = dir + "/" + lastDir;

        if (inputDir) {
          debugDev("dirStr: %o; inputDir: %o", dir, inputDir);
        }
        if (!inputDir || (dir.startsWith(inputDir) && dir !== inputDir)) {
          if (this.config.dataFileDirBaseNameOverride) {
            let indexDataFile = dir + "/" + this.config.dataFileDirBaseNameOverride;
            this._addBaseToPaths(paths, indexDataFile, userExtensions, true);
          } else {
            this._addBaseToPaths(paths, dirPathNoExt, userExtensions);
          }
        }
      }

      // 0.11.0+ include root input dir files
      // if using `docs/` as input dir, looks for docs/docs.json et al
      if (inputDir) {
        let lastInputDir = TemplatePath.addLeadingDotSlash(
          TemplatePath.join(inputDir, TemplatePath.getLastPathSegment(inputDir))
        );

        // in root input dir, search for index.11tydata.json et al
        if (this.config.dataFileDirBaseNameOverride) {
          let indexDataFile =
            TemplatePath.getDirFromFilePath(lastInputDir) +
            "/" +
            this.config.dataFileDirBaseNameOverride;
          this._addBaseToPaths(paths, indexDataFile, userExtensions, true);
        } else if (lastInputDir !== "./") {
          this._addBaseToPaths(paths, lastInputDir, userExtensions);
        }
      }
    }

    debug("getLocalDataPaths(%o): %o", templatePath, paths);
    return unique(paths).reverse();
  }

  static mergeDeep(config, target, ...source) {
    if (config.dataDeepMerge) {
      return TemplateData.merge(target, ...source);
    } else {
      return Object.assign(target, ...source);
    }
  }

  static merge(target, ...source) {
    return merge(target, ...source);
  }

  static cleanupData(data) {
    if (isPlainObject(data) && "tags" in data) {
      if (typeof data.tags === "string") {
        data.tags = data.tags ? [data.tags] : [];
      } else if (data.tags === null) {
        data.tags = [];
      }

      // Deduplicate tags
      data.tags = [...new Set(data.tags)];
    }

    return data;
  }

  async getServerlessPathData() {
    let configApiGlobalData = await this.getInitialGlobalData();
    return configApiGlobalData?.eleventy?.serverless?.path;
  }
}

module.exports = TemplateData;