import { render } from "preact-render-to-string"
import { QuartzComponent, QuartzComponentProps } from "./types"
import HeaderConstructor from "./Header"
import BodyConstructor from "./Body"
import { JSResourceToScriptElement, StaticResources } from "../util/resources"
import { FullSlug, RelativeURL, joinSegments } from "../util/path"
import { visit } from "unist-util-visit"
import { Root, Element, ElementContent } from "hast"

interface RenderComponents {
  head: QuartzComponent
  header: QuartzComponent[]
  beforeBody: QuartzComponent[]
  pageBody: QuartzComponent
  left: QuartzComponent[]
  right: QuartzComponent[]
  footer: QuartzComponent
}

export function pageResources(
  baseDir: FullSlug | RelativeURL,
  staticResources: StaticResources,
): StaticResources {
  const contentIndexPath = joinSegments(baseDir, "static/contentIndex.json")
  const contentIndexScript = `const fetchData = fetch(\`${contentIndexPath}\`).then(data => data.json())`

  return {
    css: [joinSegments(baseDir, "index.css"), ...staticResources.css],
    js: [
      {
        src: joinSegments(baseDir, "prescript.js"),
        loadTime: "beforeDOMReady",
        contentType: "external",
      },
      {
        loadTime: "beforeDOMReady",
        contentType: "inline",
        spaPreserve: true,
        script: contentIndexScript,
      },
      ...staticResources.js,
      {
        src: joinSegments(baseDir, "postscript.js"),
        loadTime: "afterDOMReady",
        moduleType: "module",
        contentType: "external",
      },
    ],
  }
}

export function renderPage(
  slug: FullSlug,
  componentData: QuartzComponentProps,
  components: RenderComponents,
  pageResources: StaticResources,
): string {
  // process transcludes in componentData
  visit(componentData.tree as Root, "element", (node, _index, _parent) => {
    if (node.tagName === "blockquote") {
      const classNames = (node.properties?.className ?? []) as string[]
      if (classNames.includes("transclude")) {
        const inner = node.children[0] as Element
        const transcludeTarget = inner.properties?.["data-slug"] as FullSlug

        // TODO: avoid this expensive find operation and construct an index ahead of time
        const page = componentData.allFiles.find((f) => f.slug === transcludeTarget)
        if (!page) {
          return
        }

        let blockRef = node.properties?.dataBlock as string | undefined
        if (blockRef?.startsWith("^")) {
          // block transclude
          blockRef = blockRef.slice(1)
          let blockNode = page.blocks?.[blockRef]
          if (blockNode) {
            if (blockNode.tagName === "li") {
              blockNode = {
                type: "element",
                tagName: "ul",
                children: [blockNode],
              }
            }

            node.children = [
              blockNode,
              {
                type: "element",
                tagName: "a",
                properties: { href: inner.properties?.href, class: ["internal"] },
                children: [{ type: "text", value: `Link to original` }],
              },
            ]
          }
        } else if (blockRef?.startsWith("#") && page.htmlAst) {
          // header transclude
          blockRef = blockRef.slice(1)
          let startIdx = undefined
          let endIdx = undefined
          for (const [i, el] of page.htmlAst.children.entries()) {
            if (el.type === "element" && el.tagName.match(/h[1-6]/)) {
              if (endIdx) {
                break
              }

              if (startIdx !== undefined) {
                endIdx = i
              } else if (el.properties?.id === blockRef) {
                startIdx = i
              }
            }
          }

          if (startIdx === undefined) {
            return
          }

          node.children = [
            ...(page.htmlAst.children.slice(startIdx, endIdx) as ElementContent[]),
            {
              type: "element",
              tagName: "a",
              properties: { href: inner.properties?.href, class: ["internal"] },
              children: [{ type: "text", value: `Link to original` }],
            },
          ]
        } else if (page.htmlAst) {
          // page transclude
          node.children = [
            {
              type: "element",
              tagName: "h1",
              children: [
                { type: "text", value: page.frontmatter?.title ?? `Transclude of ${page.slug}` },
              ],
            },
            ...(page.htmlAst.children as ElementContent[]),
            {
              type: "element",
              tagName: "a",
              properties: { href: inner.properties?.href, class: ["internal"] },
              children: [{ type: "text", value: `Link to original` }],
            },
          ]
        }
      }
    }
  })

  const {
    head: Head,
    header,
    beforeBody,
    pageBody: Content,
    left,
    right,
    footer: Footer,
  } = components
  const Header = HeaderConstructor()
  const Body = BodyConstructor()

  const LeftComponent = (
    <div class="left sidebar">
      {left.map((BodyComponent) => (
        <BodyComponent {...componentData} />
      ))}
    </div>
  )

  const RightComponent = (
    <div class="right sidebar">
      {right.map((BodyComponent) => (
        <BodyComponent {...componentData} />
      ))}
    </div>
  )

  const doc = (
    <html>
      <Head {...componentData} />
      <body data-slug={slug}>
        <div id="quartz-root" class="page">
          <Body {...componentData}>
            {LeftComponent}
            <div class="center">
              <div class="page-header">
                <Header {...componentData}>
                  {header.map((HeaderComponent) => (
                    <HeaderComponent {...componentData} />
                  ))}
                </Header>
                <div class="popover-hint">
                  {beforeBody.map((BodyComponent) => (
                    <BodyComponent {...componentData} />
                  ))}
                </div>
              </div>
              <Content {...componentData} />
            </div>
            {RightComponent}
          </Body>
          <Footer {...componentData} />
        </div>
      </body>
      {pageResources.js
        .filter((resource) => resource.loadTime === "afterDOMReady")
        .map((res) => JSResourceToScriptElement(res))}
    </html>
  )

  return "<!DOCTYPE html>\n" + render(doc)
}