import { cva, type VariantProps } from "class-variance-authority";

import { cn } from "@/lib/utils";

/**
 * Site-wide typography scale optimized for Persian (RTL) readability.
 *
 * Hierarchy (requested → variant):
 * - Heading 1 → `h1` / `display`
 * - Heading 2 → `h2`
 * - Heading 3 → `h3`
 * - Body Large → `body-lg`
 * - Body → `body`
 * - Small Text → `body-sm`
 * - Caption → `caption`
 * - Button Text → `button` / `button-lg`
 * - Navigation → `nav` / `nav-mobile`
 *
 * Alignment: prefer `text-start` (right in RTL).
 * Section captions (`section-intro`) use justify + last-line start for 2+ lines.
 * Reading measure: keep paragraphs within `typeMeasure.*` max-widths.
 *
 * Use via `typography({ variant })`, `type.*` shorthand, or `<Typography>`.
 */
export const typographyVariants = cva("tracking-normal", {
  variants: {
    variant: {
      /** Large marketing hero titles — may be centered via className */
      display:
        "text-start text-3xl font-bold leading-[1.55] text-balance sm:text-4xl lg:text-5xl",
      /** Main page titles */
      h1: "text-start text-3xl font-extrabold leading-[1.45] text-balance md:text-4xl lg:text-5xl",
      /** Major section headings */
      h2: "text-start text-2xl font-bold leading-[1.45] text-balance md:text-3xl lg:text-4xl",
      /** Subsection / feature block headings */
      h3: "text-start text-lg font-bold leading-[1.5] md:text-xl",
      /** Compact block headings, mini sections */
      h4: "text-start text-base font-bold leading-[1.5] md:text-lg",
      /** Prominent intro paragraphs — same size as section captions */
      "body-lg": "text-start text-lg leading-[1.8]",
      /** Standard paragraphs */
      body: "text-start text-base leading-[1.8]",
      /** Secondary / denser copy */
      "body-sm": "text-start text-sm leading-[1.75]",
      /** Metadata, timestamps, footnotes — fixed size site-wide */
      caption: "text-start text-xs leading-[1.6] text-muted-foreground",
      /** Dense UI chrome (mockups, compact badges, timeline steps) — prefer caption when possible */
      micro: "text-start text-[0.6875rem] leading-[1.5]",
      /** Section eyebrow / badge labels */
      eyebrow:
        "text-start text-sm font-medium leading-normal text-muted-foreground",
      /** Form labels, settings labels */
      label: "text-start text-sm font-medium leading-none",
      /** Header / menu items (desktop) */
      nav: "text-start text-sm font-medium leading-none",
      /** Mobile navigation items */
      "nav-mobile": "text-start text-base font-medium leading-snug",
      /** Default / sm button labels — optically centered in the control */
      button: "text-sm font-medium leading-none",
      /** Large button labels (hero / marketing CTAs) */
      "button-lg": "text-base font-medium leading-none",
      /** Titles inside cards and panels */
      "card-title": "text-start text-base font-bold leading-snug",
      /** Supporting copy inside cards */
      "card-desc":
        "text-start text-sm leading-[1.75] text-muted-foreground",
      /** Chat message bubbles */
      chat: "text-start text-sm leading-[1.75]",
      /** Log panels, JSON, technical output */
      code: "text-start font-mono text-xs leading-relaxed",
      /** Large stat numbers */
      stat: "text-start text-4xl font-bold leading-none text-primary md:text-5xl",
      /** Inline nav / footer links */
      link: "text-start text-sm leading-normal text-muted-foreground",
      /**
       * Section captions under headings (muted).
       * Multi-line: justify; last line stays start (right in RTL).
       * Single-line: justify has no visual stretch — stays start-aligned.
       */
      "section-intro":
        "text-justify text-lg leading-[1.8] text-muted-foreground [text-align-last:start]",
      /** Pull quotes / emphasis blocks */
      emphasis:
        "text-start text-base font-medium leading-[1.8] text-foreground",
      /** Accordion / list item titles */
      "list-title": "text-start text-base font-medium leading-snug",
      /** CTA section headings (slightly larger than h2) */
      "cta-title":
        "text-start text-2xl font-bold leading-[1.45] text-balance md:text-3xl lg:text-4xl",
      /** Decorative error page numbers */
      "display-mono":
        "text-start text-[5rem] font-black leading-none sm:text-[6rem] md:text-[8rem]",
    },
  },
  defaultVariants: {
    variant: "body",
  },
});

export type TypographyVariant = NonNullable<
  VariantProps<typeof typographyVariants>["variant"]
>;

/** Shorthand class strings for inline use: `className={type.h2}` */
export const type: Record<TypographyVariant, string> = {
  display:
    "text-3xl font-bold leading-[1.55] tracking-normal text-balance text-start sm:text-4xl lg:text-5xl",
  h1: "text-3xl font-extrabold leading-[1.45] tracking-normal text-balance text-start md:text-4xl lg:text-5xl",
  h2: "text-2xl font-bold leading-[1.45] tracking-normal text-balance text-start md:text-3xl lg:text-4xl",
  h3: "text-lg font-bold leading-[1.5] tracking-normal text-start md:text-xl",
  h4: "text-base font-bold leading-[1.5] tracking-normal text-start md:text-lg",
  "body-lg": "text-lg leading-[1.8] tracking-normal text-start",
  body: "text-base leading-[1.8] tracking-normal text-start",
  "body-sm": "text-sm leading-[1.75] tracking-normal text-start",
  caption:
    "text-xs leading-[1.6] tracking-normal text-start text-muted-foreground",
  micro: "text-[0.6875rem] leading-[1.5] tracking-normal text-start",
  eyebrow:
    "text-sm font-medium leading-normal tracking-normal text-start text-muted-foreground",
  label: "text-sm font-medium leading-none tracking-normal text-start",
  nav: "text-sm font-medium leading-none tracking-normal text-start",
  "nav-mobile": "text-base font-medium leading-snug tracking-normal text-start",
  button: "text-sm font-medium leading-none tracking-normal",
  "button-lg": "text-base font-medium leading-none tracking-normal",
  "card-title":
    "text-base font-bold leading-snug tracking-normal text-start",
  "card-desc":
    "text-sm leading-[1.75] tracking-normal text-start text-muted-foreground",
  chat: "text-sm leading-[1.75] tracking-normal text-start",
  code: "font-mono text-xs leading-relaxed tracking-normal text-start",
  stat: "text-4xl font-bold leading-none tracking-normal text-start text-primary md:text-5xl",
  link: "text-sm leading-normal tracking-normal text-start text-muted-foreground",
  "section-intro":
    "text-lg leading-[1.8] tracking-normal text-justify text-muted-foreground [text-align-last:start]",
  emphasis:
    "text-base font-medium leading-[1.8] tracking-normal text-start text-foreground",
  "list-title":
    "text-base font-medium leading-snug tracking-normal text-start",
  "cta-title":
    "text-2xl font-bold leading-[1.45] tracking-normal text-balance text-start md:text-3xl lg:text-4xl",
  "display-mono":
    "text-[5rem] font-black leading-none tracking-tighter text-start sm:text-[6rem] md:text-[8rem]",
};

/**
 * Comfortable reading widths for Persian body copy.
 * Prefer these over stretching lines across the full container.
 */
export const typeMeasure = {
  /** Short support line under a heading */
  narrow: "max-w-md",
  /** Standard paragraph / section intro */
  prose: "max-w-2xl",
  /** Longer multi-paragraph blocks */
  wide: "max-w-3xl",
} as const;

/** Text-related spacing tied to typography hierarchy */
export const typeSpacing = {
  /** Eyebrow → heading */
  eyebrowToHeading: "mt-2",
  /** Heading → supporting paragraph */
  headingToBody: "mt-3",
  /** Section title block */
  sectionStack: "space-y-4",
  /** Page hero block */
  heroStack: "space-y-6",
  /** Card title → description */
  cardStack: "gap-1.5",
  /** Stacked paragraphs */
  paragraphStack: "space-y-4",
  /** Label → input */
  labelToControl: "gap-1.5",
  /** Message → timestamp in chat */
  chatMeta: "space-y-1",
} as const;

export function typography(
  variant: TypographyVariant,
  className?: string
): string {
  return cn(typographyVariants({ variant }), className);
}