"use client"

import {
  Button,
  Table,
  TableBody,
  TableCaption,
  TableCell,
  TableHead,
  TableHeader,
  TableRow,
} from "@conusai-kit/ui/primitives"

// Imports a CSV file: the browser reads it, hashes it and sends it to the service in chunks of the size one
// request may carry, each carrying the import's revision from the chunk before. A row the service refuses
// is listed with its reason; the others stay applied. Sending the same file again applies nothing twice.

import type { ProjectSlugs } from "@conusai-kit/ui"
import { describeError, useWrite } from "@conusai-kit/ui/data"
import { serviceNotice } from "@conusai-kit/ui/patterns"
import { Alert, AlertDescription, Field, FieldDescription, FieldLabel, Input } from "@conusai-kit/ui/primitives"
import { type FormEvent, type ReactElement, useState } from "react"
import { type ImportOutcomeView, type ImportRow, MAX_IMPORT_BYTES } from "../contract/index.js"
import { chunksOf, parseProductCsv } from "./import-rows.js"

export interface ImportFormLabels {
  readonly heading: string
  readonly file: string
  readonly hint: string
  readonly submit: string
  readonly busy: string
  /** `{created} created, ...`: the component fills the counts. */
  readonly done: string
  readonly empty: string
  readonly tooLarge: string
  /** `... lacks: {columns}` */
  readonly missing: string
  readonly refusedCaption: string
  readonly row: string
  readonly reason: string
  readonly reasons: Readonly<Record<"invalid_fields" | "conflict" | "not_found", string>>
  readonly failed: string
  /** The text of each business refusal by problem code (`businessRefusalNotices` of `@conusai-kit/business/refusals`). */
  readonly refusals: Readonly<Record<string, string>>
}

type Refused = { sourceRow: number; reason: string | null }

type State =
  | { kind: "idle" }
  | { kind: "busy" }
  | { kind: "message"; text: string }
  | { kind: "done"; summary: string; refused: Refused[] }

async function sha256(bytes: ArrayBuffer): Promise<string> {
  const digest = await crypto.subtle.digest("SHA-256", bytes)
  return Array.from(new Uint8Array(digest), (byte) => byte.toString(16).padStart(2, "0")).join("")
}

export function ImportForm({ slugs, labels }: { slugs: ProjectSlugs; labels: ImportFormLabels }): ReactElement {
  const apply = useWrite<
    ProjectSlugs & {
      fileHash: string
      sourceName: string
      format: "csv"
      chunk: number
      finalChunk: boolean
      revision?: string
      rows: ImportRow[]
      requestId: string
    },
    ImportOutcomeView
  >("catalog.import.apply")
  const [state, setState] = useState<State>({ kind: "idle" })

  const submit = async (event: FormEvent<HTMLFormElement>): Promise<void> => {
    event.preventDefault()
    const file = new FormData(event.currentTarget).get("file")
    if (!(file instanceof File) || file.size === 0) return
    if (file.size > MAX_IMPORT_BYTES) {
      setState({ kind: "message", text: labels.tooLarge })
      return
    }
    setState({ kind: "busy" })
    try {
      const parsed = parseProductCsv(await file.text())
      if (parsed.kind === "unreadable") {
        setState({ kind: "message", text: labels.missing.replace("{columns}", parsed.missing.join(", ")) })
        return
      }
      const chunks = chunksOf(parsed.rows)
      if (chunks.length === 0) {
        setState({ kind: "message", text: labels.empty })
        return
      }
      const fileHash = await sha256(await file.arrayBuffer())
      const refused: Refused[] = []
      let last: ImportOutcomeView | undefined
      for (const [chunk, rows] of chunks.entries()) {
        last = await apply.mutate({
          ...slugs,
          fileHash,
          sourceName: file.name,
          format: "csv",
          chunk,
          finalChunk: chunk === chunks.length - 1,
          ...(last === undefined ? {} : { revision: last.import.revision }),
          rows,
          requestId: crypto.randomUUID(),
        })
        for (const row of last.rows) {
          if (row.outcome === "refused") refused.push({ sourceRow: row.sourceRow, reason: row.reason })
        }
      }
      const totals = last?.import
      setState({
        kind: "done",
        summary: labels.done
          .replace("{created}", String(totals?.created ?? 0))
          .replace("{updated}", String(totals?.updated ?? 0))
          .replace("{unchanged}", String(totals?.unchanged ?? 0))
          .replace("{refused}", String(totals?.refused ?? 0)),
        refused,
      })
    } catch (error) {
      setState({
        kind: "message",
        text: labels.failed.replace("{detail}", serviceNotice(error, labels.refusals)?.text ?? describeError(error)),
      })
    }
  }

  const reasonOf = (reason: string | null): string =>
    (reason !== null && labels.reasons[reason as keyof typeof labels.reasons]) || (reason ?? "")

  return (
    <form onSubmit={submit} aria-busy={state.kind === "busy"}>
      <h2>{labels.heading}</h2>
      <Field>
        <FieldLabel>{labels.file}</FieldLabel>
        <Input name="file" type="file" required accept=".csv,text/csv" />
        <FieldDescription>{labels.hint}</FieldDescription>
      </Field>
      <Button type="submit" disabled={state.kind === "busy"}>
        {state.kind === "busy" ? labels.busy : labels.submit}
      </Button>
      {state.kind === "message" ? (
        <Alert variant="destructive">
          <AlertDescription>{state.text}</AlertDescription>
        </Alert>
      ) : null}
      {state.kind === "done" ? (
        <>
          <p role="status">{state.summary}</p>
          {state.refused.length > 0 ? (
            <Table>
              <TableCaption>{labels.refusedCaption}</TableCaption>
              <TableHeader>
                <TableRow>
                  <TableHead scope="col">{labels.row}</TableHead>
                  <TableHead scope="col">{labels.reason}</TableHead>
                </TableRow>
              </TableHeader>
              <TableBody>
                {state.refused.map((row) => (
                  <TableRow key={row.sourceRow}>
                    <TableHead scope="row">{row.sourceRow}</TableHead>
                    <TableCell>{reasonOf(row.reason)}</TableCell>
                  </TableRow>
                ))}
              </TableBody>
            </Table>
          ) : null}
        </>
      ) : null}
    </form>
  )
}