// State of the reader: the document, the view (in force / previews), the
// language the text is read in, and the panel (which unit, which version,
// which tab) — the panel lives in the URL so a link reopens it, as does the
// vote unfolded under an article (`?vote=`).

import { api, ApiError } from './api';
import type { GroupView } from './group';
import type { DocView, Lang, PreviewUnit, Proposal, Translation, Unit } from './types';

export type View = 'inforce' | 'wellrated' | 'all';
/** The panel: the basket of the vote, the versions of an article, a new proposal, the details of a version, the formula. */
export type Tab = 'basket' | 'proposals' | 'propose' | 'details' | 'settings';

export interface PanelState {
  unitId: string | null;
  proposalId: string | null;
  tab: Tab;
  draftId?: string | null;
  /** The basket, opened on one section. */
  section?: string | null;
  prefill?: { title: string; body: string } | null;
  /** A new proposal that answers this objection (ADR 0010). */
  objectionId?: string | null;
  /** The details of one's own version, its edit form open: to reword it. */
  edit?: boolean;
}

/** The tabs as the URL names them. */
export const TABS: Record<string, Tab> = { panier: 'basket', propositions: 'proposals', proposer: 'propose', details: 'details', reglages: 'settings' };
export const TAB_NAMES: Record<Tab, string> = { basket: 'panier', proposals: 'propositions', propose: 'proposer', details: 'details', settings: 'reglages' };

/** The query of a reader's URL: the unfolded vote and the panel. */
export function panelSearch(panel: PanelState | null, vote: string | null): string {
  const q = new URLSearchParams();
  if (vote) q.set('vote', vote);
  if (panel) {
    q.set('onglet', TAB_NAMES[panel.tab]);
    if (panel.unitId) q.set('article', panel.unitId);
    if (panel.proposalId) q.set('version', panel.proposalId);
    if (panel.draftId) q.set('brouillon', panel.draftId);
    if (panel.section) q.set('section', panel.section);
    if (panel.objectionId) q.set('objection', panel.objectionId);
    if (panel.edit) q.set('modifier', '1');
  }
  return q.toString();
}

export interface Shown {
  title: string;
  body: string;
  /** The text is a translation (editorial). */
  translated: boolean;
  stale: boolean;
  /** Asked for a translation that does not exist yet: the source is shown. */
  missing: boolean;
}

export function shown(
  v: { title: string; body: string; translations: Partial<Record<Lang, Translation>> },
  lang: Lang,
  source: Lang,
): Shown {
  if (lang === source) return { title: v.title, body: v.body, translated: false, stale: false, missing: false };
  const tr = v.translations[lang];
  if (!tr) return { title: v.title, body: v.body, translated: false, stale: false, missing: true };
  return { title: tr.title, body: tr.body, translated: true, stale: tr.stale, missing: false };
}

export class DocState {
  view = $state<DocView | null>(null);
  error = $state<string | null>(null);
  mode = $state<View>('inforce');
  preview = $state<PreviewUnit[] | null>(null);
  original = $state(false);

  async load(group: string, slug: string) {
    try {
      const g = await api.get<GroupView>(`/groups/${group}`);
      const d = g.docs.find((x) => x.slug === slug);
      if (!d) {
        this.error = g.group.open ? 'not_found' : 'forbidden';
        return;
      }
      this.view = await api.get<DocView>(`/docs/${d.id}`);
      this.error = null;
      if (this.mode !== 'inforce') await this.loadPreview();
    } catch (e) {
      this.error = e instanceof ApiError ? e.code : 'internal';
    }
  }

  async reload() {
    if (!this.view) return;
    this.view = await api.get<DocView>(`/docs/${this.view.doc.id}`);
    if (this.mode !== 'inforce') await this.loadPreview();
  }

  async setMode(mode: View) {
    this.mode = mode;
    if (mode === 'inforce') this.preview = null;
    else await this.loadPreview();
  }

  async loadPreview() {
    if (!this.view) return;
    const r = await api.get<{ units: PreviewUnit[] }>(`/docs/${this.view.doc.id}/preview?mode=${this.mode}`);
    this.preview = r.units;
  }

  /** The modules of the document (ADR 0009): its title, then the order of each section. */
  get modules(): Unit[] {
    const m = this.view?.modules;
    return m ? [...(m.title ? [m.title] : []), ...m.orders] : [];
  }

  /** The order of a section, when it has something to decide (two articles or more). */
  orderOf(section: string | null): Unit | undefined {
    return this.view?.modules.orders.find((o) => o.section === section && !o.moot);
  }

  /** An article or a module. */
  unit(id: string | null): Unit | undefined {
    return this.view?.units.find((u) => u.id === id) ?? this.modules.find((u) => u.id === id);
  }

  proposal(id: string | null): Proposal | undefined {
    if (!id || !this.view) return undefined;
    for (const u of [...this.view.units, ...this.modules]) {
      if (u.inForce?.id === id) return u.inForce;
      const p = u.proposals.find((x) => x.id === id);
      if (p) return p;
    }
    return undefined;
  }

  get inForce(): Unit[] {
    return (this.view?.units ?? []).filter((u) => u.inForce);
  }

  /**
   * Articles and modules in document order (ADR 0009): the title first, then the
   * articles of each section followed by its order, when it has something to decide.
   */
  get ordered(): Unit[] {
    const m = this.view?.modules;
    const out: Unit[] = m?.title ? [m.title] : [];
    const units = this.view?.units ?? [];
    units.forEach((u, i) => {
      out.push(u);
      if (units[i + 1]?.section === u.section) return;
      const order = this.orderOf(u.section);
      if (order) out.push(order);
    });
    return out;
  }

  /**
   * The text in force by section, each closed by its order (ADR 0009) — shown even
   * where no article is in force yet, as long as it has something to decide.
   */
  get inForceBySection(): { section: string | null; units: Unit[]; order: Unit | undefined }[] {
    const out: { section: string | null; units: Unit[]; order: Unit | undefined }[] = [];
    for (const u of this.view?.units ?? []) {
      let last = out.at(-1);
      if (!last || last.section !== u.section) {
        last = { section: u.section, units: [], order: this.orderOf(u.section) };
        out.push(last);
      }
      if (u.inForce) last.units.push(u);
    }
    return out.filter((s) => s.units.length || s.order);
  }

  /** Open proposals, of articles and modules, in document order; drafts apart. */
  get open(): { unit: Unit; proposal: Proposal }[] {
    const out: { unit: Unit; proposal: Proposal }[] = [];
    for (const unit of this.ordered) {
      for (const proposal of unit.proposals) if (proposal.status === 'open') out.push({ unit, proposal });
    }
    return out;
  }

  /** The title of an article as it is read: its text in force, else its latest open text. */
  articleTitle(id: string, lang: Lang, source: Lang): string {
    const u = this.view?.units.find((x) => x.id === id);
    if (!u) return id;
    const v = u.inForce ?? u.proposals.findLast((p) => p.status === 'open' && p.kind === 'text');
    return v ? shown(v, lang, source).title : u.code;
  }

  get drafts(): { unit: Unit; proposal: Proposal }[] {
    const out: { unit: Unit; proposal: Proposal }[] = [];
    for (const unit of this.view?.units ?? []) {
      for (const proposal of unit.proposals) if (proposal.status === 'draft') out.push({ unit, proposal });
    }
    return out;
  }
}