// based on basicSetup https://github.com/codemirror/basic-setup/blob/main/src/codemirror.ts

const editorSrc = `
import {
  keymap, highlightSpecialChars, 
  drawSelection, highlightActiveLine, dropCursor,
  rectangularSelection, crosshairCursor,
  lineNumbers, highlightActiveLineGutter,
  EditorView
} from '@codemirror/view'
import {EditorState} from '@codemirror/state'
import {
  defaultHighlightStyle,
  syntaxHighlighting,
  indentOnInput, 
  bracketMatching,
  foldGutter,
  foldKeymap
} from '@codemirror/language'
import {
  defaultKeymap,
  history,
  historyKeymap
} from '@codemirror/commands'
import {
  searchKeymap,
  highlightSelectionMatches
} from '@codemirror/search'
import {
  autocompletion,
  completionKeymap,
  closeBrackets,
  closeBracketsKeymap
} from '@codemirror/autocomplete'
import {lintKeymap} from '@codemirror/lint'

console.log('loading file')

const basicSetup = (() => [
  lineNumbers(),
  highlightActiveLineGutter(),
  highlightSpecialChars(),
  history(),
  foldGutter(),
  drawSelection(),
  dropCursor(),
  EditorState.allowMultipleSelections.of(true),
  indentOnInput(),
  syntaxHighlighting(defaultHighlightStyle, {fallback: true}),
  bracketMatching(),
  closeBrackets(),
  autocompletion(),
  rectangularSelection(),
  crosshairCursor(),
  highlightActiveLine(),
  highlightSelectionMatches(),
  keymap.of([
    ...closeBracketsKeymap,
    ...defaultKeymap,
    ...searchKeymap,
    ...historyKeymap,
    ...foldKeymap,
    ...completionKeymap,
    ...lintKeymap
  ])
])()

window.editorLib = {
  basicSetup,
  EditorView
}`

class Builder {
  // any URL that supports pkg/path or pkg@version/path
  baseUrl = 'https://unpkg.com'
  scripts = {
    '@rollup/browser': {
      version: '3.20.4',
      path: 'dist/rollup.browser.js',
      sha: 'sha256-GgOznxZmgghx1a7CH09B+VmDKtziPO5tAnC5gC+/5Kw=',
    },
  }

  topLevelDeps = [
    "@codemirror/autocomplete",
    "@codemirror/commands",
    "@codemirror/language",
    "@codemirror/lint",
    "@codemirror/search",
    "@codemirror/state",
    "@codemirror/view",
    "@codemirror/lang-javascript",
  ]

  constructor() {
    this.downloads = []
  }

  checkOk(resp) {
    if (!resp.ok) {
      throw new Error(`HTTP request failed: ${resp.status}`)
    }
  }

  async loadDep(dep) {
    this.scripts[dep] = {}
    const pkgResp = await fetch(
      `${this.baseUrl}/${dep}/package.json`
    )
    this.checkOk(pkgResp)
    this.log(dep)
    const pkg = await pkgResp.json()
    this.scripts[dep].version = pkg.version
    this.scripts[dep].path = (
      pkg.module ?? pkg.main
    )
    this.downloads.push(this.getScript(dep))
    const deps = Object.keys(
      pkg.dependencies || {}
    ).filter(dep => !(dep in this.scripts))
    await Promise.allSettled(deps.map(dep => (
      this.loadDep(dep)
    )))
  }

  async sha(ab) {
    const hash = await crypto.subtle.digest(
      "SHA-256", ab
    )
    return 'sha256-' + btoa(
      String.fromCharCode(
        ...new Uint8Array(hash)
      )
    )
  }

  async checkIntegrity(resp, name, script) {
    const blob = await resp.blob()
    const ab = await blob.arrayBuffer()
    const sha = await this.sha(ab)
    if (sha !== script.sha) {
      throw new Error(
        'failed integrity check: ' +
        `${checkValue} !== ${script.sha}`
      )
    }
    return ab
  }

  async getScript(name) {
    this.log('[downloading] ' + name, 'green')
    const script = this.scripts[name]
    if (script.text) {
      return script.text
    }
    const url = (
      `${this.baseUrl}/${name}@${script.version}/` +
      script.path
    )
    const resp = await fetch(url)
    this.checkOk(resp)
    if (script.sha) {
      const ab = await this.checkIntegrity(
        resp, name, script
      )
      script.text = new TextDecoder().decode(ab)
    } else {
      script.text = await resp.text()
      script.sha = resp.integrity
    }
    this.log(
      '[downloaded] ' + url + ` [${script.text.length}]`,
      'green'
    )
    return script.text
  }

  async loadScript(name) {
    const text = await this.getScript(name)
    const s = document.createElement('script')
    s.text = text
    document.head.append(s)
  }

  get loaderPlugin() {
    return {
      name: 'loader',
      resolveId: async source => {
        if (source === 'editor.js' || source in this.scripts) {
          return source
        }
      },
      load: async id => {
        if (id === 'editor.js') {
          this.log(`[found] editor.js`)
          return editorSrc
        } else if (id in this.scripts) {
          this.log(`[found] ${id}`)
          return this.scripts[id].text
        }
      },
    }
  }

  async build() {
    const result = await Promise.all(
      this.topLevelDeps.map(dep => (
        this.loadDep(dep)
      ))
    )
    await Promise.all(this.downloads)
    await this.loadScript('@rollup/browser')
    const { rollup } = window.rollup
    const input = 'editor.js'
    const plugins = [this.loaderPlugin]
    const bundle = await rollup({input, plugins})
    const {output} = await bundle.generate({format: 'es'})
    this.code = output[0].code
    this.sha = await this.sha(
      new TextEncoder().encode(this.code)
    )
    this.log(`built ${this.sha}`)
  }
}

class BuildView extends HTMLElement {
  constructor() {
    super()
    this.attachShadow({mode: 'open'})
    this.shadowRoot.adoptedStyleSheets = [
      this.constructor.styleSheet
    ]
  }

  log(message, cls = 'cyan') {
    const el = document.createElement('pre')
    el.classList.add(cls)
    el.innerText = message
    this.shadowRoot.append(el)
    ;(el.scrollIntoViewIfNeeded ?? el.scrollIntoView).call(el)
  }

  static get styleSheet() {
    if (this._styleSheet === undefined) {
      this._styleSheet = new CSSStyleSheet()
      this._styleSheet.replaceSync(this.css)
    }
    return this._styleSheet
  }

  static css = `
    :host {
      display: flex;
      flex-direction: column;
      align-items: stretch;
      margin: 10px;
      gap: 10px;
    }

    pre {
      padding: 8px;
      border-radius: 5px;
      margin: 0;
      overflow-x: auto;
    }

    pre.cyan {
      background: cyan;
    }

    pre.green {
      background: lightgreen;
    }
  `
}

class Editor extends HTMLElement {
  constructor() {
    super()
    this.attachShadow({mode: 'open'})
    this.shadowRoot.adoptedStyleSheets = [
      this.constructor.styleSheet
    ]
  }

  connectedCallback() {
    const {EditorView, basicSetup} = window.editorLib
    this.view = new EditorView({
      doc: '',
      extensions: [
        basicSetup,
      ],
      root: this.shadowRoot,
    })
    this.shadowRoot.append(this.view.dom)
  }

  static get styleSheet() {
    if (this._styleSheet === undefined) {
      this._styleSheet = new CSSStyleSheet()
      this._styleSheet.replaceSync(this.css)
    }
    return this._styleSheet
  }

  static css = `
    :host {
      display: flex;
      flex-direction: column;
      align-items: stretch;
      height: 33vh;
      background-color: #fff;
      border: 5px solid red
    }
    :host > * {
      flex-grow: 1;
    }
  `
}

customElements.define('m-build-view', BuildView)
customElements.define('m-editor', Editor)

class App {
  constructor() {
    this.builder = new Builder()
    this.buildView = document.createElement('m-build-view')
    document.body.append(this.buildView)
    this.builder.log = this.buildView.log.bind(this.buildView)
    this.run()
  }

  async run() {
    await this.build()
    await this.display()
  }

  async build() {
    try {
      await this.builder.build()
      const s = document.createElement('script')
      s.type = 'module'
      s.textContent = this.builder.code
      document.head.append(s)
      this.buildView.log('skipped appending code')
      //this.buildView.log(this.builder.code)
    } catch (e) {
      this.buildView.log(`${e}`)
    }
  }

  async display() {
    await new Promise(r => setTimeout(() => r(), 500))
    this.editor = document.createElement('m-editor')
    document.body.append(this.editor)
  }
}

new App()