// SPDX-License-Identifier: LicenseRef-ConusAI-Template-1.0
import { businessRefusalNotices, businessServiceNotices } from "@conusai-kit/business/refusals"
import { type Container, notFound, serviceRefusal, type TransportCaller } from "@conusai-kit/core"
import type { I18n } from "@conusai-kit/i18n"
import { Decimal, Money } from "@conusai-kit/money"
import { Quantity } from "@conusai-kit/money/units"
import { type ProjectPage, projectPage } from "@conusai-kit/ui"
import { Can } from "@conusai-kit/ui/data"
import {
  FactList,
  Page,
  PageHeader,
  PageSection,
  type ServiceNotice,
  ServiceStatePage,
  serviceNotice,
} from "@conusai-kit/ui/patterns"
import * as contracts from "../contract/index.js"
import { en } from "../i18n/en.js"
import { FiscalAction, InvoiceForm, Invoices, SeriesForm, UblDownload } from "./controls.js"
import type { Labels, Messages } from "./labels.js"

type Data = { labels: Labels } & (
  | {
      kind: "list"
      invoices: { rows: contracts.InvoiceView[]; after?: string | undefined }
      series: contracts.SeriesView[]
    }
  | {
      kind: "invoice"
      invoice: contracts.InvoiceView
      series: contracts.SeriesView[]
      /** The amounts, quantities and rates as the reader writes them, formatted on the server. */
      shown: { payable: string; lines: string[] }
    }
  | { kind: "state"; notice: ServiceNotice }
)
export const invoicingPage: ProjectPage<TransportCaller, I18n, Container, Data> = projectPage({
  async load({ slugs, segments, caller, i18n }) {
    const messages = Object.fromEntries(
      Object.keys(en).map((key) => [key, i18n.message(`invoicing.${key}`)]),
    ) as Messages
    const labels: Labels = {
      ...messages,
      locale: i18n.locale,
      refusals: businessRefusalNotices(i18n.locale, {
        conflict: messages.conflict,
        revision_conflict: messages.conflict,
        invalid: messages.invalid,
      }),
    }
    const [id, ...rest] = segments
    if (rest.length || (id !== undefined && !contracts.invoiceId.safeParse(id).success)) throw notFound()
    try {
      const allSeries: contracts.SeriesView[] = []
      let after: string | undefined
      const seen = new Set<string>()
      let pages = 0
      // Numbering choices are bounded; refusal is preferable to silently missing a series.
      do {
        if (pages++ >= 20) throw serviceRefusal("degraded")
        const page = await caller.call(contracts.series, { org: slugs.org, ...(after ? { after } : {}) })
        allSeries.push(...page.rows)
        after = page.after
        if (allSeries.length > 1000 || (after && seen.has(after))) throw serviceRefusal("degraded")
        if (after) seen.add(after)
      } while (after)
      if (id === undefined)
        return {
          kind: "list",
          labels,
          invoices: await caller.call(contracts.invoices, { org: slugs.org }),
          series: allSeries,
        }
      const invoice = await caller.call(contracts.invoice, { org: slugs.org, invoiceId: id })
      return { kind: "invoice", labels, invoice, series: allSeries, shown: shownOf(invoice, labels, i18n) }
    } catch (error) {
      const notice = serviceNotice(error, businessServiceNotices(i18n.locale))
      if (!notice) throw error
      return { kind: "state", labels, notice }
    }
  },
  View({ slugs, data }) {
    const labels = data.labels
    const href = `/${slugs.org}/${slugs.workspace}/${slugs.project}/invoicing`
    if (data.kind === "state") return <ServiceStatePage title={labels.title} notice={data.notice} />
    if (data.kind === "list")
      return (
        <Page>
          <PageHeader title={labels.title} description={labels.intro} />
          <p>{labels.fiscalNotice}</p>
          <Invoices slugs={slugs} seed={data.invoices} href={href} labels={labels} />
          <Can permission="invoicing.invoice.write">
            <InvoiceForm slugs={slugs} labels={labels} series={data.series} href={href} />
          </Can>
          <Can permission="invoicing.series.manage">
            <SeriesForm slugs={slugs} labels={labels} />
          </Can>
        </Page>
      )
    const invoice = data.invoice
    return (
      <Page>
        <PageHeader
          title={invoice.number ?? labels.draft}
          description={`${labels[invoice.status]} · ${data.shown.payable}`}
        />
        <a href={href}>{labels.back}</a>
        <p>{labels.fiscalNotice}</p>
        <PageSection title={labels.saved}>
          <FactList
            facts={[
              { label: labels.revision, value: invoice.revision },
              { label: labels.seller, value: invoice.data.seller.name },
              { label: labels.buyer, value: invoice.data.buyer.name },
              { label: labels.issueDate, value: invoice.data.issue_date },
              { label: labels.dueDate, value: invoice.data.due_date ?? "—" },
              { label: labels.currency, value: invoice.data.currency },
              { label: labels.buyerReference, value: invoice.data.buyer_reference },
              ...invoice.data.lines.map((line, index) => ({
                label: line.item_name,
                value: data.shown.lines[index] ?? "",
              })),
              { label: labels.payable, value: data.shown.payable },
            ]}
          />
        </PageSection>
        {invoice.status === "draft" ? (
          <>
            <Can permission="invoicing.invoice.write">
              <InvoiceForm slugs={slugs} invoice={invoice} labels={labels} series={data.series} href={href} />
            </Can>
            <Can permission="invoicing.invoice.issue">
              <FiscalAction slugs={slugs} invoice={invoice} operation="issue" series={data.series} labels={labels} />
            </Can>
          </>
        ) : null}
        {invoice.status === "issued" ? (
          <>
            <Can permission="invoicing.invoice.credit">
              <FiscalAction slugs={slugs} invoice={invoice} operation="credit" series={data.series} labels={labels} />
            </Can>
            <Can permission="invoicing.invoice.void">
              <FiscalAction slugs={slugs} invoice={invoice} operation="void" series={data.series} labels={labels} />
            </Can>
          </>
        ) : null}
        {invoice.status !== "draft" ? (
          <PageSection title={labels.download}>
            <UblDownload slugs={slugs} invoice={invoice} labels={labels} />
          </PageSection>
        ) : null}
      </Page>
    )
  },
})

/** Exact values in the reader's form (`12,50 €`, `3 vnt.`, `21 %`), never through a float. */
function shownOf(invoice: contracts.InvoiceView, labels: Labels, i18n: I18n): { payable: string; lines: string[] } {
  return {
    payable: i18n.money(Money.parse(invoice.payable)),
    lines: invoice.data.lines.map((line) =>
      [
        `${i18n.quantity(Quantity.of(line.quantity, line.unit))} × ${i18n.money(Money.parse(line.net_price))}`,
        `${labels.vatCategory}: ${line.vat_category}`,
        `${labels.vatRate}: ${line.vat_rate ? i18n.percent(Decimal.parse(line.vat_rate)) : "—"}`,
        ...(line.exemption_reason ? [line.exemption_reason] : []),
      ].join(" · "),
    ),
  }
}