"use strict";

const fs = require("fs");
const Case = require("case");
const hyperfast = require("hyperfast");
const indent = require("indent-string");

const postDateFormatter = new Intl.DateTimeFormat("en-GB", {
  hour12: false,
  weekday: "long",
  year: "numeric",
  month: "long",
  day: "numeric"
});

const getTemplate = name =>
  fs.readFileSync(`${__dirname}/templates/${name}.html`, "utf8");

function getTemplateIndent(re, template) {
  return re.exec(getTemplate(template))[1].length;
}
const findMain = /^(\s+)<main/m;
const baseIndentLevel = getTemplateIndent(findMain, "layout");
const findPostContent = /^(\s+)<div class="post-content/m;
const postIndentLevel =
  baseIndentLevel + getTemplateIndent(findPostContent, "post");

function indentForTemplate(text, indentLevel) {
  return indent(text, indentLevel).slice(indentLevel).replace(/\n+$/, "");
}

function templateReader(template, indentLevel) {
  return indentForTemplate(getTemplate(template), indentLevel);
}

const templates = {
  layout: templateReader("layout"),
  home: templateReader("home", baseIndentLevel),
  post: templateReader("post", baseIndentLevel),
  taxon: templateReader("taxon", baseIndentLevel)
};

function title(siteTitle, pageTitle) {
  return pageTitle ? `${pageTitle} · ${siteTitle}` : siteTitle;
}

const makeTime = date => ({
  datetime: date.toISOString(),
  _text: postDateFormatter.format(date)
});

const renderPostListItem = ctx => post => {
  return {
    time: makeTime(post.data.get("date")),
    a: {
      href: ctx.getURL("post", post.basename),
      _text: post.data.get("title")
    }
  };
};

function layout(config, pageTitle, pageElement) {
  return hyperfast(templates.layout, {
    title: title(config.site.author.name, pageTitle),
    "body > header .p-name": config.site.author.name,
    "body > header .u-photo": {
      alt: config.site.author.name,
      src: config.site.author.photo
    },
    "body > main": pageElement.outerHTML
  }).outerHTML.trim();
}

module.exports = {
  baseIndentLevel,
  postIndentLevel,
  indentForTemplate,

  home(ctx, config, posts) {
    ctx.type = "html";

    ctx.body = layout(
      config,
      null,
      hyperfast(templates.home, {
        ".post": posts.map(renderPostListItem(ctx))
      })
    );
  },

  post(ctx, config, post) {
    ctx.type = "html";

    ctx.body = layout(
      config,
      post.data.get("title"),
      hyperfast(templates.post, {
        "article h1": post.data.get("title"),
        "article time": makeTime(post.data.get("date")),
        "article .post-content": {
          _html: post.body
        }
      })
    );
  },

  taxon(ctx, config, term, value, taxonItems) {
    ctx.type = "html";

    ctx.body = layout(
      config,
      Case.title(value),
      hyperfast(templates.taxon, {
        ".post": taxonItems.map(renderPostListItem(ctx))
      })
    );
  }
};