package tui

import (
	"image/color"

	"charm.land/lipgloss/v2"
)

// tuiTheme is the resolved terminal palette Zero renders with. It is produced by
// buildTheme from a palette, so the same renderers serve both the dark default
// and the light variant; the active theme lives in the package var zeroTheme and
// may be swapped at startup (background detection / ZERO_THEME / --theme) or live
// via /theme. Colors are truecolor hex; lipgloss downsamples on limited displays
// and renders plain text when there is no TTY (tests). Every renderer consumes
// these named styles — no hex literal may appear outside theme_palettes.go (the
// palette tables + theme registry).
type tuiTheme struct {
	// Base tokens.
	ink        lipgloss.Style // primary text
	muted      lipgloss.Style // secondary text, assistant interim prose
	faint      lipgloss.Style // hints, metadata
	faintest   lipgloss.Style // line numbers, separators, tool args
	accent     lipgloss.Style // brand lime: prompts, spinner, focus
	green      lipgloss.Style // success, diff add sign, ✓
	red        lipgloss.Style // errors, diff del sign, ✗, deny
	amber      lipgloss.Style // permission surfaces, warnings, auto badge
	blue       lipgloss.Style // grep file locations, local-model dot
	gitAdd     lipgloss.Style // PR/local diff additions
	gitDel     lipgloss.Style // PR/local diff deletions
	line       lipgloss.Style // default borders, rules, status separators
	lineStrong lipgloss.Style // emphasized borders
	selection  lipgloss.Style // transcript selection highlight
	hover      lipgloss.Style // hovered clickable row (specialist card, toggle, sidebar/plan row)

	// Title bar.
	badge lipgloss.Style // ` 0 ` brand chip: onAccent on accent, bold

	// Stream roles.
	userPrompt lipgloss.Style // ❯ user gutter, accent bold
	sayText    lipgloss.Style // assistant interim prose, muted

	// Tool cards.
	toolName   lipgloss.Style // head-row tool name, ink bold
	toolTarget lipgloss.Style // head-row target path, ink
	toolArg    lipgloss.Style // one-line arg hint, faintest
	cardRun    lipgloss.Style // card border while the call runs (accent-mixed)
	cardErr    lipgloss.Style // card border after an error (red-mixed)
	bashPrompt lipgloss.Style // ❯ command gutter inside bash cards, accent bold
	grepLoc    lipgloss.Style // file:line locations in grep bodies, blue

	// Diff bodies. The sign/count styles are bare foregrounds; the line styles
	// carry the tinted backgrounds standing in for the prototype's 9% overlays.
	// Gutter and sign columns get their own bg-carrying styles because lipgloss
	// resets the background between adjacent Render calls — every segment of a
	// tinted row must carry the tint itself.
	diffAdd     lipgloss.Style // + sign in counts
	diffDel     lipgloss.Style // − sign in counts
	diffMeta    lipgloss.Style // @@ hunks, +++/--- headers
	addLine     lipgloss.Style // added-line text: addInk on addBg
	delLine     lipgloss.Style // deleted-line text: delInk on delBg
	addLineWord lipgloss.Style // the changed span within an added line: addInk on the brighter addBgWord
	delLineWord lipgloss.Style // the changed span within a deleted line: delInk on the brighter delBgWord
	addLineNum  lipgloss.Style // gutter number on addBg
	delLineNum  lipgloss.Style // gutter number on delBg
	addSign     lipgloss.Style // + column on addBg
	delSign     lipgloss.Style // − column on delBg
	delText     lipgloss.Style // delInk as bare foreground (stderr-ish output)

	// Permission surfaces.
	permBadge  lipgloss.Style // PERMISSION chip: onAccent on amber, bold
	permBg     lipgloss.Style // permission card body tint
	permBorder lipgloss.Style // permission card border (amber-mixed line)

	// Surfaces.
	panel           lipgloss.Style // bare panel background (card padding, body fill)
	userPromptPanel lipgloss.Style // submitted user prompt background

	// Permission modes.
	modeAuto   lipgloss.Style
	modeAsk    lipgloss.Style
	modeUnsafe lipgloss.Style

	// Raw colors a few renderers paint/interpolate with directly (the streaming
	// fade interpolates accent→ink; panel-backed prompts paint on bgPanel), kept
	// on the theme so a theme switch reaches them too. The bg* colors back the
	// on* surface helpers below.
	accentColor color.Color
	inkColor    color.Color
	bgPanel     color.Color
	bgPrompt    color.Color
	bgSel       color.Color
	bgPerm      color.Color
}

// palette is the raw color-token table for one theme. buildTheme turns it into a
// resolved tuiTheme. The palette literals and the ordered theme registry live in
// theme_palettes.go (the only place hex literals live). Dark palettes keep tints
// darker than ink so every pairing survives 256-color downsampling; light palettes
// are dark-on-light with the same intent inverted.
type palette struct {
	panel     string // card backgrounds (the terminal canvas itself is never painted full-bleed)
	promptBg  string // submitted user prompt background
	line      string // default borders, rules
	line2     string // emphasized borders
	ink       string // primary text
	muted     string // secondary text
	faint     string // hints, metadata
	faintest  string // line numbers, separators, tool args
	accent    string // brand lime
	green     string // success, diff add
	red       string // errors, diff del
	amber     string // permission, warnings
	blue      string // grep locations, local-model dot
	gitAdd    string // footer PR diff additions
	gitDel    string // footer PR diff deletions
	addBg     string // diff added-line bg
	delBg     string // diff deleted-line bg
	addBgWord string // diff added-line changed-span bg (brighter than addBg)
	delBgWord string // diff deleted-line changed-span bg (brighter than delBg)
	permBg    string // permission card bg
	selBg     string // selected row bg
	addInk    string // added-line text
	delInk    string // deleted-line text
	onAccent  string // text on accent or amber fills
	cardRun   string // running card border (accent mixed into line)
	cardErr   string // errored card border (red mixed into line)
	cardPerm  string // permission card border (amber mixed into line)
}

// buildTheme resolves a palette into the styles every renderer uses.
func buildTheme(p palette) tuiTheme {
	col := func(s string) color.Color { return lipgloss.Color(s) }
	fg := func(s string) lipgloss.Style { return lipgloss.NewStyle().Foreground(col(s)) }
	return tuiTheme{
		ink:        fg(p.ink),
		muted:      fg(p.muted),
		faint:      fg(p.faint),
		faintest:   fg(p.faintest),
		accent:     fg(p.accent).Bold(true),
		green:      fg(p.green),
		red:        fg(p.red),
		amber:      fg(p.amber),
		blue:       fg(p.blue),
		gitAdd:     fg(p.gitAdd),
		gitDel:     fg(p.gitDel),
		line:       fg(p.line),
		lineStrong: fg(p.line2),
		selection:  lipgloss.NewStyle().Background(col(p.accent)).Foreground(col(p.onAccent)),
		// A full block (like selection) would be too heavy for something that
		// repaints on every mouse movement; a soft foreground reads as
		// "interactive" at a glance without competing with real content colors
		// (e.g. a specialist card's red/green status glyph). Amber (not the brand
		// lime accent) — lime read as too glaring for something that repaints
		// continuously as the cursor moves.
		hover: fg(p.amber),

		badge: lipgloss.NewStyle().Background(col(p.accent)).Foreground(col(p.onAccent)).Bold(true),

		userPrompt: fg(p.accent).Bold(true),
		sayText:    fg(p.muted),
		toolName:   fg(p.ink).Bold(true),
		toolTarget: fg(p.ink),
		toolArg:    fg(p.faintest),
		cardRun:    fg(p.cardRun),
		cardErr:    fg(p.cardErr),
		bashPrompt: fg(p.accent).Bold(true),
		grepLoc:    fg(p.blue),

		diffAdd:     fg(p.green),
		diffDel:     fg(p.red),
		diffMeta:    fg(p.faintest),
		addLineWord: lipgloss.NewStyle().Foreground(col(p.addInk)).Background(col(p.addBgWord)),
		delLineWord: lipgloss.NewStyle().Foreground(col(p.delInk)).Background(col(p.delBgWord)),
		addLine:     lipgloss.NewStyle().Foreground(col(p.addInk)).Background(col(p.addBg)),
		delLine:     lipgloss.NewStyle().Foreground(col(p.delInk)).Background(col(p.delBg)),
		addLineNum:  lipgloss.NewStyle().Foreground(col(p.faintest)).Background(col(p.addBg)),
		delLineNum:  lipgloss.NewStyle().Foreground(col(p.faintest)).Background(col(p.delBg)),
		addSign:     lipgloss.NewStyle().Foreground(col(p.green)).Background(col(p.addBg)),
		delSign:     lipgloss.NewStyle().Foreground(col(p.red)).Background(col(p.delBg)),
		delText:     fg(p.delInk),

		permBadge:  lipgloss.NewStyle().Background(col(p.amber)).Foreground(col(p.onAccent)).Bold(true),
		permBg:     lipgloss.NewStyle().Background(col(p.permBg)),
		permBorder: fg(p.cardPerm),

		panel:           lipgloss.NewStyle().Background(col(p.panel)),
		userPromptPanel: lipgloss.NewStyle().Background(col(p.promptBg)),

		modeAuto: fg(p.green).Bold(true),
		// The steady "ask" footer label is calm (un-bolded) so it doesn't compete
		// with the transient bold-amber permission badge (permBadge) shown when a
		// tool is actually asking right now — a glance separates state from event.
		modeAsk:    fg(p.amber),
		modeUnsafe: fg(p.red).Bold(true),

		accentColor: col(p.accent),
		inkColor:    col(p.ink),
		bgPanel:     col(p.panel),
		bgPrompt:    col(p.promptBg),
		bgSel:       col(p.selBg),
		bgPerm:      col(p.permBg),
	}
}

// zeroTheme is the active palette every renderer reads. It defaults to dark and is
// reassigned by theme selection at startup and by /theme. All references are
// .field accesses evaluated at render time, so reassigning this var repaints every
// subsequent render.
var zeroTheme = buildTheme(darkPalette)

// onPanel returns a copy of style that paints on the panel surface. lipgloss
// resets the background between adjacent Render calls, so every segment of a
// panel row (including padding) must carry the background itself — renderers wrap
// their foreground styles through this instead of referencing hex.
func (t tuiTheme) onPanel(style lipgloss.Style) lipgloss.Style {
	return style.Background(t.bgPanel)
}

// onSel paints on the selected-row tint.
func (t tuiTheme) onSel(style lipgloss.Style) lipgloss.Style {
	return style.Background(t.bgSel)
}