package tui

import "strings"

// ─── Component-level background painting ─────────────────────────────────────

//

// Components call paintBgWith() to apply themed background colors to their

// rendered lines. Colors come from ActiveTheme() which is set at startup

// via DetectTheme() (dark/light auto-detection matching upstream).

//

// Upstream reference: tui/src/utils.ts:applyBackgroundToLine,

// components/box.ts:applyBg, theme/dark.json, theme/light.json.

// Convenience accessors for component code that paints backgrounds.

// These read from the active theme so dark/light mode works automatically.

func UserMessageBgOpen() string { return ActiveTheme().UserMessageBg }

func ToolPendingBgOpen() string { return ActiveTheme().ToolPendingBg }

func ToolSuccessBgOpen() string { return ActiveTheme().ToolSuccessBg }

func ToolErrorBgOpen() string { return ActiveTheme().ToolErrorBg }

func BgClose() string { return ActiveTheme().BgClose }

// paintBgWith wraps `line` in the given bg-open SGR + bgClose, padded

// to `width` visible columns. Visible width respects ANSI escapes (via

// lineDisplayWidth). Used by UserMessageBlock and ToolExecutionComponent.

//

// Body renderers (read, write, edit) emit \x1b[0m (full SGR reset) inside

// their styled lines. A bare open+line+close approach would lose the bg

// tint at every reset point, leaving "uncolored pixels" for the remainder

// of the line. This function re-applies `open` after every \x1b[0m so the

// bg tint is continuous regardless of embedded resets.

//

// If `width <= visibleLen(line)` the function emits exactly the line

// with no trailing padding (still bg-wrapped): caller is responsible

// for clamping over-width content before paint.

func paintBgWith(open, line string, width int) string {

// Replace tabs with spaces: terminals don't reliably paint bg

// color through tab stops, causing visible gaps in tinted boxes.

line = strings.ReplaceAll(line, "\t", " ")

visLen := lineDisplayWidth(line)

pad := max(width-visLen, 0)

bgClose := ActiveTheme().BgClose

// Re-apply bg after any full SGR reset inside the line so body

// renderers that use \x1b[0m for dim/color don't break the bg tint.

// Also handle the shorter \x1b[m form (semantically identical, used

// by grep --color and many other tools).

if open != "" && strings.Contains(line, "\x1b[") {

// Strip \x1b[K (erase-to-EOL): it would clear the bg paint from

// the current position to the end of the terminal row using whatever

// bg color is active at that point.

line = strings.ReplaceAll(line, "\x1b[K", "")

line = strings.ReplaceAll(line, "\x1b[0m", "\x1b[0m"+open)

line = strings.ReplaceAll(line, "\x1b[m", "\x1b[m"+open)

}

// The padding ends the line, as upstream applyBackgroundToLine pads to width

// (utils.ts:1099-1108); an erase-to-end-of-line here would change the cells a

// fullscreen frame leaves past the padding.

return open + line + strings.Repeat(" ", pad) + bgClose

}