import { ActionQueue } from './actions'
import { el, fmt, icon, jsonAttr, labelsFor, uiLocaleOf, type Labels } from './labels'

export const GRAPH_TAG = 'golem15-seo-graph'

/** One missing property of a node. */
export interface GraphFinding {
  level: 'required' | 'recommended'
  property: string
}

/** A node of the graph with its findings. */
export interface GraphNode {
  id: string
  type: string
  findings: GraphFinding[]
  rules: boolean
}

/** The seo_graph action's answer (UI-SPEC C18). */
export interface GraphData {
  locale: string
  url: string | null
  graph: Record<string, unknown> | null
  nodes: GraphNode[]
}

interface Payload {
  op: 'graph'
  locale: string
}

/** The Rich Results Test address of a page. */
export function richResultsURL(url: string): string {
  return 'https://search.google.com/test/rich-results?url=' + encodeURIComponent(url)
}

/** The fragment of an @id (#article), the whole id when it has none. */
function fragment(id: string): string {
  const i = id.indexOf('#')
  return i >= 0 ? id.slice(i) : id
}

/**
 * E9 golem15-seo-graph (UI-SPEC C18, D-46): the effective @graph of the
 * saved page with the unsaved seo_schema value, every node with Google's
 * required and recommended findings, the JSON and the Rich Results Test
 * link. It asks through summer-action only ({op: graph, locale}), on
 * connect, 800 ms after the last fill change and on the ML locale switch.
 */
export class SeoGraphElement extends HTMLElement {
  static observedAttributes = ['fill-values', 'busy', 'state', 'ui-locale', 'disabled', 'label']

  private data: GraphData | null = null
  private failed = false
  private pending = false
  private showJSON = false
  private shownLocale = ''
  private lastFill = ''
  private timer: ReturnType<typeof setTimeout> | undefined
  private connected = false
  private readonly actions = new ActionQueue<Payload>(this, () => this.fail())

  private readonly onResult = (ev: Event): void => {
    const detail = (ev as CustomEvent).detail as { data?: unknown } | undefined
    this.actions.settle()
    const data = detail?.data as GraphData | undefined
    if (data && Array.isArray(data.nodes)) {
      this.data = data
      this.failed = false
    }
    this.pending = this.actions.current !== null
    this.render()
  }

  private readonly onLocale = (ev: Event): void => {
    const locale = (ev as CustomEvent).detail
    if (typeof locale === 'string' && locale !== '' && locale !== this.shownLocale) {
      this.shownLocale = locale
      this.check()
    }
  }

  connectedCallback(): void {
    this.connected = true
    this.lastFill = this.getAttribute('fill-values') ?? ''
    this.addEventListener('summer-result', this.onResult)
    window.addEventListener('summer:ml-locale', this.onLocale)
    this.render()
    queueMicrotask(() => {
      if (this.connected) {
        this.check()
      }
    })
  }

  disconnectedCallback(): void {
    this.connected = false
    this.removeEventListener('summer-result', this.onResult)
    window.removeEventListener('summer:ml-locale', this.onLocale)
    clearTimeout(this.timer)
    this.actions.reset()
    this.pending = false
  }

  attributeChangedCallback(name: string, _old: string | null, value: string | null): void {
    if (!this.connected) {
      return
    }
    if (name === 'busy' && value === null) {
      this.actions.flush()
      return
    }
    if (name === 'state' && value === 'error') {
      if (this.actions.settle()) {
        this.fail()
      }
      return
    }
    if (name === 'fill-values') {
      const fill = value ?? ''
      if (fill !== this.lastFill) {
        this.lastFill = fill
        clearTimeout(this.timer)
        this.timer = setTimeout(() => this.check(), 800)
      }
      return
    }
    this.render()
  }

  private labels(): Labels {
    return labelsFor(uiLocaleOf(this))
  }

  /** Asks for the graph of the shown locale (one queued request at most). */
  check(): void {
    clearTimeout(this.timer)
    this.pending = true
    this.actions.request({ op: 'graph', locale: this.shownLocale })
    this.render()
  }

  private fail(): void {
    this.failed = true
    this.pending = this.actions.current !== null
    this.render()
  }

  private render(): void {
    if (!this.connected) {
      return
    }
    const labels = this.labels()
    const sections: HTMLElement[] = []
    this.setAttribute('aria-busy', String(this.pending))
    const data = this.data

    const header = el('p', 'seo-graph__meta')
    if (data) {
      header.textContent = data.url ? fmt(labels.forLocale, { locale: (data.locale || '').toUpperCase(), url: data.url }) : labels.graphNoUrl
    }
    if (this.pending) {
      const line = el('p', 'seo-graph__meta seo-graph__checking', labels.graphChecking)
      line.setAttribute('role', 'status')
      sections.push(line)
    }
    if (data) {
      sections.push(header)
      const list = el('div', 'seo-graph__nodes')
      let problems = 0
      for (const node of data.nodes) {
        const row = el('div', 'seo-graph__node')
        const head = el('div', 'seo-graph__node-head')
        head.append(el('span', 'seo-graph__pill', node.type || '—'), el('code', 'seo-graph__id', fragment(node.id || '')))
        row.append(head)
        if (!node.rules) {
          row.append(el('p', 'seo-graph__meta', fmt(labels.noRules, { type: node.type })))
        }
        for (const f of node.findings ?? []) {
          problems++
          const required = f.level === 'required'
          const line = el('p', 'seo-graph__finding seo-graph__finding--' + (required ? 'required' : 'recommended'))
          line.append(icon(required ? 'circle-alert' : 'triangle-alert'), el('span', '', fmt(required ? labels.required : labels.recommended, { property: f.property, type: node.type })))
          row.append(line)
        }
        list.append(row)
      }
      sections.push(list)
      if (problems === 0 && data.nodes.length > 0) {
        const ok = el('p', 'seo-graph__ok')
        ok.append(icon('circle-check'), el('span', '', labels.allGood))
        sections.push(ok)
      }
      if (data.graph) {
        const toggle = el('button', 'seo-graph__disclosure')
        toggle.type = 'button'
        toggle.setAttribute('aria-expanded', String(this.showJSON))
        toggle.append(el('span', '', this.showJSON ? labels.hideJson : labels.showJson), icon('chevron-down'))
        toggle.addEventListener('click', () => {
          this.showJSON = !this.showJSON
          this.render()
        })
        sections.push(toggle)
        if (this.showJSON) {
          sections.push(el('pre', 'seo-graph__json', JSON.stringify(data.graph, null, 2)))
        }
      }
      const notes = el('div', 'seo-graph__links')
      if (data.url) {
        const link = el('a', 'seo-graph__link')
        link.href = richResultsURL(data.url)
        link.target = '_blank'
        link.rel = 'noopener'
        link.append(el('span', '', labels.richResults), icon('external-link'))
        notes.append(link)
      }
      notes.append(el('p', 'seo-graph__meta', labels.graphUnsaved), el('p', 'seo-graph__meta', labels.layerNodes))
      sections.push(notes)
    }
    if (this.failed) {
      const line = el('p', 'seo-graph__error')
      line.setAttribute('role', 'status')
      line.append(icon('circle-alert'), el('span', '', labels.graphFailed))
      sections.push(line)
    }
    if (!this.hasAttribute('disabled')) {
      const button = el('button', 'seo-graph__button', this.getAttribute('label') || labels.graphAction)
      button.type = 'button'
      button.addEventListener('click', () => this.check())
      sections.push(button)
    }
    this.replaceChildren(...sections)
  }

  /** The fill snapshot (seo_schema), for tests. */
  fill(): Record<string, unknown> {
    return jsonAttr<Record<string, unknown>>(this, 'fill-values', {})
  }
}