import clsx from "clsx";

// The paint of the two button primitives (docs/DESIGN.md A1, A2, B1, B3), apart from the components so
// a LINK can wear exactly the same face (`LinkButton`): a download or a sign-in that navigates is an
// <a>, and a hand-painted look-alike beside the real buttons is how the two drifted. Every hover carries
// the `act:` variant (index.css), which stands down on a disabled or busy control and fits a link too.

export type ButtonVariant =
  | "primary" // solid accent — the main affirmative action
  | "danger" // solid danger — destructive confirm
  | "warn" // solid warn — the action of a warning bar (reload for a new version)
  | "outline" // bordered, quiet — secondary action (Full history, Subscribe, Cancel-with-border)
  | "outline-accent" // bordered + accent-tinted — an affirmative secondary (Activate, Approve)
  | "outline-danger" // neutral at rest, danger on hover — a row-level Delete
  | "outline-warn" // bordered + warn-tinted — a reversible restriction that is currently ON
  | "ghost" // borderless — tertiary/dismiss (dialog Cancel, close)
  | "glass" // glass card — the Plex/overlay action buttons (A1: glass is a variant, not a hand-built one)
  | "overlay" // white text on the always-dark player chrome, whatever the theme
  | "media" // dark translucent on a picture — "From the start" on a card (C5); always round
  | "danger-soft" // bordered AND danger-coloured at rest — a destructive action that shouldn't shout
  | "link" // inline accent text — "Show all", "Learn more", a resend-mail prompt inside a sentence
  | "link-muted"; // inline quiet text that brightens on hover — "Clear", "Show less", "Skip"

export type ButtonSize =
  | "xs" // 24 — inside a table row
  | "sm" // 28 — toolbars and panel headers; lines up with the search pill and the dropdown trigger
  | "md" // 32 — forms and dialog footers
  | "lg" // 40 — a page's single hero call to action (Welcome, onboarding), nowhere else
  | "none"; // no box of its own — the link variants' default

// B3: every hover and press is a LAYER (the `state-*` utilities in index.css), never an opacity dim or
// a `bg-card` fill, which vanish on a light card. The utilities already stand down on a disabled, busy
// or pressed button; the text-colour hovers here carry the same guard as a variant.
const BUTTON_VARIANTS: Record<ButtonVariant, string> = {
  primary: "font-medium state-filled",
  danger: "font-medium state-danger",
  warn: "font-medium state-warn",
  outline: "font-medium border border-border text-muted state-layer act:hover:text-fg",
  "outline-accent": "font-medium border border-accent/40 text-accent state-layer",
  // Neutral until you reach for it. NOT `danger-soft`, which is already red at rest — the difference
  // is whether the button should advertise the destruction before the pointer arrives.
  "outline-danger":
    "font-medium border border-border text-muted state-layer act:hover:text-danger act:hover:border-danger/40",
  "outline-warn": "font-medium border border-warn/40 text-warn state-layer",
  ghost: "font-medium text-muted state-layer act:hover:text-fg",
  glass: "font-medium glass-card glass-hover act:hover:text-accent",
  // The player chrome is dark in the light theme too: a theme-fg state layer would be a dark wash.
  overlay: "font-medium text-white/80 act:hover:text-white act:hover:bg-white/15",
  media: "font-medium bg-black/60 text-white act:hover:bg-black/75",
  "danger-soft":
    "font-medium border border-danger/60 text-danger state-layer act:hover:border-danger",
  link: "font-semibold text-accent act:hover:underline",
  "link-muted": "font-medium text-muted act:hover:text-fg",
};

// A pressed toggle (`pressed`) is the solid accent in every variant (B3: "selected stays the solid
// accent"); the layer utilities leave it alone, so it stays solid under the pointer too.
const PRESSED =
  "aria-pressed:bg-accent aria-pressed:text-accent-fg aria-pressed:border-accent aria-pressed:no-underline";

// B1, the whole ladder: explicit heights, so a toolbar's `sm` button, search pill, dropdown trigger and
// small icon button all line up at 28. A call site picks a rung; it does not invent one. rem-derived, so
// the Settings text-size slider (--font-scale) grows the box with the label. A1: r8 on every rung; a
// button on a picture, or nested in a pill (the header search's Go), is a pill instead (A2: round
// means "floats over something", and a pill's inner button follows its radius).
const SIZES: Record<ButtonSize, string> = {
  xs: "h-6 px-2 text-xs gap-1 whitespace-nowrap",
  sm: "h-7 px-2.5 text-sm gap-1.5 whitespace-nowrap",
  md: "h-8 px-3 text-sm gap-1.5 whitespace-nowrap",
  lg: "h-10 px-4 text-base gap-2 whitespace-nowrap",
  // No box of its own, but still a 24 target on a mouse (B1).
  none: "gap-1.5 min-h-6",
};

// The font-weight is owned by each VARIANT, not by BASE: `link` wants semibold (that is what a text
// link looks like everywhere in this app) and the action buttons want medium. Two font-* utilities on
// one element is a coin flip without tailwind-merge, so exactly one has to emit it — see the test.
const BASE =
  "inline-flex shrink-0 items-center justify-center transition disabled:opacity-50 disabled:cursor-not-allowed aria-disabled:opacity-50 aria-disabled:cursor-not-allowed [&>svg]:size-4 [&>svg]:shrink-0";

export type IconButtonVariant =
  | "ghost" // the default: quiet glyph, a state layer on hover
  | "ghost-accent" // an accent glyph: the action it stands for is already in effect (queued, requested)
  | "primary" // solid accent — the one affirmative action of a compact form (Send, Save view)
  | "outline" // bordered — an icon action that stands on its own in a form or a header
  | "outline-accent" // bordered + accent — an affirmative row action (Approve)
  | "outline-danger" // bordered, danger on hover — a row's destructive action beside bordered siblings
  | "outline-warn" // bordered + warn — a reversible restriction that is currently ON (Suspended)
  | "danger" // quiet at rest, danger on hover — a row's delete/remove
  | "danger-soft" // bordered AND danger at rest — a destructive restriction that is ON (Blocked)
  | "glass" // glass card — beside the glass Buttons on a Plex page
  | "media" // round, dark translucent — on a thumbnail or a poster
  | "overlay"; // white glyph on the always-dark player chrome, whatever the theme

export type IconButtonSize =
  | "sm" // 28 — rows and dense toolbars
  | "md" // 32 — on its own
  | "lg" // 48 — only the Play in the middle of a picture (C5: a not-started card)
  | "player"; // 36 with a 20px glyph, 44 on touch (A3) — the Plex player's control row (C5)

const ICON_VARIANTS: Record<IconButtonVariant, string> = {
  ghost: "text-muted state-layer act:hover:text-fg",
  "ghost-accent": "text-accent state-layer",
  primary: "state-filled",
  outline: "border border-border text-muted state-layer act:hover:text-fg",
  "outline-accent": "border border-accent/40 text-accent state-layer",
  "outline-danger":
    "border border-border text-muted state-layer act:hover:text-danger act:hover:border-danger/40",
  "outline-warn": "border border-warn/40 text-warn state-layer",
  danger: "text-muted state-layer act:hover:text-danger",
  "danger-soft": "border border-danger/60 text-danger state-layer act:hover:border-danger",
  glass: "glass-card glass-hover act:hover:text-accent",
  // The player chrome and a thumbnail are dark in the light theme too, so these two paint with
  // white and black, not with the theme's fg (whose state layer would be a dark wash on a dark video).
  media: "bg-black/60 text-white act:hover:bg-black/75",
  overlay: "text-white/80 act:hover:text-white act:hover:bg-white/15",
};

// An icon toggle that is on shows it in the glyph (watched, saved, a selected track), not as a solid
// fill: a solid accent square in a row of quiet glyphs outshouts the row's primary action.
const ICON_PRESSED = "aria-pressed:text-accent";

const ICON_SIZES: Record<IconButtonSize, string> = {
  sm: "size-7 [&>svg]:size-4",
  md: "size-8 [&>svg]:size-4",
  lg: "size-12 [&>svg]:size-6",
  player: "size-9 [&>svg]:size-5",
};

export const isLinkVariant = (v: ButtonVariant) => v === "link" || v === "link-muted";

export function buttonClass({
  variant,
  size,
  round = false,
  fullWidth = false,
  pressed,
}: {
  variant: ButtonVariant;
  size: ButtonSize;
  round?: boolean;
  fullWidth?: boolean;
  pressed?: boolean;
}) {
  return clsx(
    BASE,
    BUTTON_VARIANTS[variant],
    pressed !== undefined && PRESSED,
    SIZES[size],
    size !== "none" && (round || variant === "media" ? "rounded-full" : "rounded-lg"),
    // The coarse-pointer target (DESIGN.md A3) lives HERE, not in the call sites — on every variant.
    // The link variants were once excluded as "a run of text inside a sentence", but none is: every
    // one stands on its own ("See all", "Forgot your passphrase?", a notification's action), and the
    // an audit measured them at 16–20px on a tablet. Text inside a sentence is a plain <a>.
    "touch-target",
    fullWidth && "w-full",
  );
}

export function iconButtonClass({
  variant,
  size,
  round = false,
  pressed,
}: {
  variant: IconButtonVariant;
  size: IconButtonSize;
  round?: boolean;
  pressed?: boolean;
}) {
  return clsx(
    "inline-grid shrink-0 place-items-center transition touch-target aria-expanded:text-accent disabled:opacity-50 disabled:cursor-not-allowed aria-disabled:opacity-50 aria-disabled:cursor-not-allowed",
    ICON_VARIANTS[variant],
    round || variant === "media" ? "rounded-full" : "rounded-lg",
    pressed !== undefined && ICON_PRESSED,
    ICON_SIZES[size],
  );
}