import type { ComponentType } from "react";
import { effectiveMargins, type MarginPreset, type PageFrame, type Sides } from "../engine/geometry";
import type { Rect } from "../engine/layoutTree";
import type { SlotLogoPlacement } from "../engine/logo";
import type { RoleName, RoleTable, TypeToken } from "../fonts/roles";
import type { DecorItem } from "../blocks/FirstPageHeader";
import type { RenderModel } from "../model/build";
import type { RenderPrefsV1 } from "../model/prefs";
import type { TemplateSlot } from "./slots.types";

/** A logo after fitting and the stack-or-side-by-side decision (engine/logo.ts). */
export interface PlacedLogo {
  dataUri: string;
  w: number;
  h: number;
  stacked: boolean;
  /** Set for slot-based templates: where the reference placeholder was and how the logo was fitted to it. */
  placement?: SlotLogoPlacement;
  /** Where the fitted logo sits inside the slot's target box (pt from its top-left), so a flow layout can reproduce the alignment. */
  slotOffset?: { x: number; y: number };
}

/** What the page itself carries besides the flow: the paper, the ink and every-page art. */
export interface TemplateDecor {
  /** Page fill (the Page backgroundColor), e.g. Serenity's paper. Omitted: white. */
  background?: string;
  /** Default text colour of the page. */
  ink: string;
  /** Fixed every-page decor in page space; must stay clear of the content column. */
  everyPage?: (frame: PageFrame) => DecorItem[];
  /** Page-space boxes the flow must stay out of (audited as `keepout`). */
  keepOuts?: (frame: PageFrame) => Rect[];
}

/** Footer and page-label chrome of a template. */
export interface TemplateChrome {
  color: string;
  /** Hairline above the footer (Classic); null for none. */
  rule: string | null;
  /** Footer type (a render-prop role: no leading). Default: the "footer" role. */
  role?: RoleName | TypeToken;
  /** The footer text starts and ends this far inside the content column. */
  inset?: { left: number; right: number };
  /** Width the left footer text (supplier name) is fitted to. */
  leftWidth: number;
  /** Height reserved at the foot of every page for the footer line; default FOOTER_RESERVE (it includes Classic's rule). */
  reserve?: number;
}

export interface TemplateProps {
  model: RenderModel;
  frame: PageFrame;
  logo: PlacedLogo | null;
  prefs: RenderPrefsV1;
}

export interface TemplateDefinition {
  id: string;
  name: string;
  family: string;
  /** Static PNG for the template picker, served from /public (written by scripts/thumbnails.mjs). */
  thumbnail: string;
  /** Shown on the picker tile. */
  badge?: "Matches your original format";
  /** The template's own type roles (Classic's are TYPE_ROLES). */
  roles: RoleTable;
  decor: TemplateDecor;
  chrome: TemplateChrome;
  /** Bump when the layout changes in a way that alters pages; it goes into the PDF Creator string. */
  version: number;
  /** The template's own physical margins (the "template" margin preset). */
  margins: Sides;
  /** No margin preset may go below this, per side; the printer-safe floor still applies on top. */
  marginFloor: Sides;
  logo: {
    /** The largest box the logo may fill, pt. */
    box: { w: number; h: number };
    /** The logo moves above the text when the text beside it would be narrower than this. */
    stackBelowTextWidth: number;
    defaultOn: boolean;
    /** Width of the column the logo shares with the supplier text, for this frame. */
    slotWidth: (frame: PageFrame) => number;
    /**
     * The measured reference placeholder (or opt-in area) the user's logo replaces, from slotFor(id).
     * Null for Classic, which fits its logo with computeClassicLogoPlacement.
     */
    slot: TemplateSlot | null;
    /** The template has no placeholder: the logo is shown only when the user turns it on (prefs.logo.show). */
    optIn?: boolean;
    /** Room the layout can really give the logo; the slot's target box shrinks to it. */
    available?: (frame: PageFrame) => { w: number; h: number };
  };
  Layout: ComponentType<TemplateProps>;
}

/** Physical margins for a template under a margin preset. */
export function marginsFor(template: TemplateDefinition, preset: MarginPreset): Sides {
  return effectiveMargins(preset === "template" ? template.margins : preset, template.marginFloor);
}