const fs = require("fs");
const { TemplatePath } = require("@11ty/eleventy-utils");

// const debug = require("debug")("Eleventy:TemplateLayoutPathResolver");

class TemplateLayoutPathResolver {
  constructor(path, inputDir, extensionMap, eleventyConfig) {
    if (!eleventyConfig) {
      throw new Error("Expected `eleventyConfig` in TemplateLayoutPathResolver constructor");
    }
    this.eleventyConfig = eleventyConfig;
    this.inputDir = inputDir;
    this.originalPath = path;
    this.path = path;
    this.aliases = {};
    this.extensionMap = extensionMap;
    if (!extensionMap) {
      throw new Error("Expected `extensionMap` in TemplateLayoutPathResolver constructor.");
    }

    this.init();
  }

  setAliases() {
    this.aliases = Object.assign({}, this.config.layoutAliases, this.aliases);
  }

  set inputDir(dir) {
    this._inputDir = dir;
    this.dir = this.getLayoutsDir();
  }

  get inputDir() {
    return this._inputDir;
  }

  // for testing
  set config(cfg) {
    this._config = cfg;
    this.dir = this.getLayoutsDir();
    this.init();
  }

  get config() {
    if (this.eleventyConfig) {
      return this.eleventyConfig.getConfig();
    } else {
      throw new Error("Missing this.eleventyConfig");
    }
  }

  init() {
    // we might be able to move this into the constructor?
    this.aliases = Object.assign({}, this.config.layoutAliases, this.aliases);
    // debug("Current layout aliases: %o", this.aliases);

    if (this.path in this.aliases) {
      // debug(
      //   "Substituting layout: %o maps to %o",
      //   this.path,
      //   this.aliases[this.path]
      // );
      this.path = this.aliases[this.path];
    }

    let useLayoutResolution = this.config.layoutResolution;

    this.pathAlreadyHasExtension = this.dir + "/" + this.path;

    if (this.path.split(".").length > 0 && fs.existsSync(this.pathAlreadyHasExtension)) {
      this.filename = this.path;
      this.fullPath = TemplatePath.addLeadingDotSlash(this.pathAlreadyHasExtension);
    } else if (useLayoutResolution) {
      this.filename = this.findFileName();
      this.fullPath = TemplatePath.addLeadingDotSlash(this.dir + "/" + this.filename);
    }
  }

  addLayoutAlias(from, to) {
    this.aliases[from] = to;
  }

  getFileName() {
    if (!this.filename) {
      throw new Error(
        `You’re trying to use a layout that does not exist: ${this.originalPath} (${this.filename})`
      );
    }

    return this.filename;
  }

  getFullPath() {
    if (!this.filename) {
      throw new Error(
        `You’re trying to use a layout that does not exist: ${this.originalPath} (${this.filename})`
      );
    }

    return this.fullPath;
  }

  findFileName() {
    if (!fs.existsSync(this.dir)) {
      throw Error(
        "TemplateLayoutPathResolver directory does not exist for " + this.path + ": " + this.dir
      );
    }

    for (let filename of this.extensionMap.getFileList(this.path)) {
      // TODO async
      if (fs.existsSync(this.dir + "/" + filename)) {
        return filename;
      }
    }
  }

  getLayoutsDir() {
    let layoutsDir;
    if ("layouts" in this.config.dir) {
      layoutsDir = this.config.dir.layouts;
    } else if ("includes" in this.config.dir) {
      layoutsDir = this.config.dir.includes;
    } else {
      // Should this have a default?
      layoutsDir = "_includes";
    }

    return TemplatePath.join(this.inputDir, layoutsDir);
  }

  getNormalizedLayoutKey() {
    return TemplatePath.stripLeadingSubPath(this.fullPath, this.getLayoutsDir());
  }
}

module.exports = TemplateLayoutPathResolver;