// Which logo an organization's pages show, and where one is fetched from. A file of the contract
// because the organization layout, the settings page's preview and the share image and email all
// need the same answer, and a rule that three places each re-derive is a rule that drifts.
//
// An organization has up to two logos, one for each theme: `light` is the logo for a light page,
// `dark` the one for a dark page. The fallback is one sentence and this file is where it is kept:
//
//   A theme shows its own logo. When only one is uploaded it shows on both themes. When none is,
//   the app brand's logo for that theme shows (config/src/brand.ts).
//
// The first two sentences are `tenantLogo`; the third is what `resolveLogo` adds.

import type { BrandView, LogoVariant } from "./view.js"

/** The two stored sizes of a raster logo, 1x and 2x (`@conusai-kit/brand/logo`'s standard set). */
export const LOGO_SIZES = ["1x", "2x"] as const
export type LogoSize = (typeof LOGO_SIZES)[number]

export interface LogoChoice {
  /** Whose logo it is: the organization's own, or the app brand's. */
  readonly source: "tenant" | "app"
  /** Which of that source's two logos was chosen; it differs from the theme asked for when the other one stood in. */
  readonly variant: LogoVariant
  /** The path of that logo on this app's origin. */
  readonly path: string
}

const other = (variant: LogoVariant): LogoVariant => (variant === "light" ? "dark" : "light")

const pathOf = (brand: Pick<BrandView, "logoLight" | "logoDark">, variant: LogoVariant): string | null =>
  variant === "light" ? brand.logoLight : brand.logoDark

/** The organization's logo for a theme: its own, else the other theme's, else null. */
export function tenantLogo(brand: Pick<BrandView, "logoLight" | "logoDark">, theme: LogoVariant): LogoChoice | null {
  for (const variant of [theme, other(theme)]) {
    const path = pathOf(brand, variant)
    if (path !== null) return { source: "tenant", variant, path }
  }
  return null
}

/** The logo for a theme: the organization's (`tenantLogo`), or, when it has none, the app brand's own for that theme. */
export function resolveLogo(
  brand: Pick<BrandView, "logoLight" | "logoDark"> | null,
  app: Readonly<Record<LogoVariant, string>>,
  theme: LogoVariant,
): LogoChoice {
  return (brand === null ? null : tenantLogo(brand, theme)) ?? { source: "app", variant: theme, path: app[theme] }
}

/** The address of one stored size of an organization's logo: its path, which carries the content tag, and the size. */
export const logoUrl = (path: string, size: LogoSize): string => `${path}${path.includes("?") ? "&" : "?"}s=${size}`