"use client"

// "Delete my account": the person types the account's e-mail address and confirms, from a session
// whose sign-in is recent (the server checks both; this form only says so first). The answer is the
// deletion's state: completed, or erasing while a module's service is unavailable -- in both cases the
// person is signed out everywhere, and the app's browser modules clear what they kept (`onDeleted`).

import { useTransport } from "@conusai-kit/ui"
import { type FormEvent, type ReactElement, useId, useState } from "react"
import type { DeletionView } from "../contract/procedures.js"

export interface AccountDeletionLabels {
  readonly heading: string
  readonly body: string
  /** The services whose data is erased, already named; empty when there are none besides the app. */
  readonly services: string
  /** Set when the person is the last owner of an organization others belong to: the form is closed. */
  readonly lastOwner?: string
  /** Set when an organization would be left without members. */
  readonly onlyMember?: string
  readonly reauth: string
  readonly reauthLink: string
  readonly notInteractive: string
  readonly confirmLabel: string
  readonly confirmHint: string
  readonly submit: string
  readonly busy: string
  readonly completed: string
  /** With `{modules}` still in it. */
  readonly erasing: string
  readonly home: string
  /** The app's `app.failed` message, with `{detail}` still in it. */
  readonly failed: string
  readonly sectionNames: Readonly<Record<string, string>>
}

export interface AccountDeletionProps {
  readonly labels: AccountDeletionLabels
  /** Whether the session may delete now: a person, signed in recently, owning no organization alone. */
  readonly interactive: boolean
  readonly recentSignIn: boolean
  /** Where a person signs in again and comes back to this page. */
  readonly reauthHref: string
  /** A deletion already under way, when the page was rendered. */
  readonly deletion: DeletionView | null
  /** Runs once the deletion answered, before the result is shown: the app ends its browser modules' context. */
  readonly onDeleted?: (deletion: DeletionView) => Promise<unknown> | unknown
}

type State =
  | { readonly kind: "idle" | "busy" }
  | { readonly kind: "deleted"; readonly deletion: DeletionView }
  | { readonly kind: "failed"; readonly detail: string; readonly code: string }

const codeOf = (error: unknown): string => {
  const problem = (error as { problem?: { code?: unknown } } | null)?.problem
  return typeof problem?.code === "string" ? problem.code : "unknown"
}

export function AccountDeletionPanel(props: AccountDeletionProps): ReactElement {
  const { labels } = props
  const { call, describe } = useTransport()
  const headingId = useId()
  const inputId = useId()
  const hintId = useId()
  const [state, setState] = useState<State>(
    props.deletion ? { kind: "deleted", deletion: props.deletion } : { kind: "idle" },
  )

  const submit = async (event: FormEvent<HTMLFormElement>): Promise<void> => {
    event.preventDefault()
    const confirm = String(new FormData(event.currentTarget).get("confirm") ?? "").trim()
    if (confirm.length === 0) return
    setState({ kind: "busy" })
    try {
      const deletion = (await call("account.deletion.request", { confirm })) as DeletionView
      // The session is revoked now: what the browser modules kept for it goes too (contract §12).
      await Promise.resolve(props.onDeleted?.(deletion)).catch(() => undefined)
      setState({ kind: "deleted", deletion })
    } catch (error) {
      setState({ kind: "failed", detail: describe(error), code: codeOf(error) })
    }
  }

  const reauth = (
    <p role="status">
      {labels.reauth} <a href={props.reauthHref}>{labels.reauthLink}</a>
    </p>
  )

  if (state.kind === "deleted") {
    const pending = state.deletion.pending.map((key) => labels.sectionNames[key] ?? key).join(", ")
    return (
      <section aria-labelledby={headingId}>
        <h2 id={headingId}>{labels.heading}</h2>
        <p role="status">
          {state.deletion.state === "completed" ? labels.completed : labels.erasing.replace("{modules}", pending)}
        </p>
        <a href="/">{labels.home}</a>
      </section>
    )
  }

  const blocked = !props.interactive || labels.lastOwner !== undefined
  return (
    <section aria-labelledby={headingId}>
      <h2 id={headingId}>{labels.heading}</h2>
      <p>{labels.body}</p>
      {labels.services ? <p>{labels.services}</p> : null}
      {labels.onlyMember ? <p>{labels.onlyMember}</p> : null}
      {labels.lastOwner ? <p role="status">{labels.lastOwner}</p> : null}
      {!props.interactive ? <p role="status">{labels.notInteractive}</p> : null}
      {props.interactive && !props.recentSignIn ? reauth : null}
      {blocked ? null : (
        <form onSubmit={submit} aria-busy={state.kind === "busy"}>
          <div className="kit-field">
            <label htmlFor={inputId}>{labels.confirmLabel}</label>
            <input
              id={inputId}
              name="confirm"
              type="email"
              required
              autoComplete="off"
              spellCheck={false}
              aria-describedby={hintId}
            />
            <p id={hintId}>{labels.confirmHint}</p>
          </div>
          <button type="submit" disabled={state.kind === "busy"}>
            {state.kind === "busy" ? labels.busy : labels.submit}
          </button>
        </form>
      )}
      {state.kind === "failed" && state.code === "reauthentication_required" ? reauth : null}
      {state.kind === "failed" && state.code !== "reauthentication_required" ? (
        <p role="alert" className="app-error">
          {labels.failed.replace("{detail}", state.detail)}
        </p>
      ) : null}
    </section>
  )
}