amfora/config/theme.go

package config

import (
	"fmt"
	"sync"

	"github.com/gdamore/tcell/v2"
)

// Functions to allow themeing configuration.
// UI element colors are mapped to a string key, such as "error" or "tab_bg"
// These are the same keys used in the config file.

var themeMu = sync.RWMutex{}
var theme = map[string]tcell.Color{
	// Default values below

	"bg":              tcell.ColorBlack, // Used for cview.Styles.PrimitiveBackgroundColor
	"tab_num":         tcell.Color30,    // xterm:Turquoise4, #008787
	"tab_divider":     tcell.ColorWhite,
	"bottombar_label": tcell.Color30,
	"bottombar_text":  tcell.ColorBlack,
	"bottombar_bg":    tcell.ColorWhite,
	"scrollbar":       tcell.ColorWhite,

	// Modals
	"btn_bg":   tcell.ColorNavy, // All modal buttons
	"btn_text": tcell.ColorWhite,

	"dl_choice_modal_bg":      tcell.ColorPurple,
	"dl_choice_modal_text":    tcell.ColorWhite,
	"dl_modal_bg":             tcell.Color130, // xterm:DarkOrange3, #af5f00
	"dl_modal_text":           tcell.ColorWhite,
	"info_modal_bg":           tcell.ColorGray,
	"info_modal_text":         tcell.ColorWhite,
	"error_modal_bg":          tcell.ColorMaroon,
	"error_modal_text":        tcell.ColorWhite,
	"yesno_modal_bg":          tcell.ColorPurple,
	"yesno_modal_text":        tcell.ColorWhite,
	"tofu_modal_bg":           tcell.ColorMaroon,
	"tofu_modal_text":         tcell.ColorWhite,
	"subscription_modal_bg":   tcell.Color61, // xterm:SlateBlue3, #5f5faf
	"subscription_modal_text": tcell.ColorWhite,

	"input_modal_bg":         tcell.ColorGreen,
	"input_modal_text":       tcell.ColorWhite,
	"input_modal_field_bg":   tcell.ColorBlue,
	"input_modal_field_text": tcell.ColorWhite,

	"bkmk_modal_bg":         tcell.ColorTeal,
	"bkmk_modal_text":       tcell.ColorWhite,
	"bkmk_modal_label":      tcell.ColorYellow,
	"bkmk_modal_field_bg":   tcell.ColorBlue,
	"bkmk_modal_field_text": tcell.ColorWhite,

	"hdg_1":             tcell.ColorRed,
	"hdg_2":             tcell.ColorLime,
	"hdg_3":             tcell.ColorFuchsia,
	"amfora_link":       tcell.Color33, // xterm:DodgerBlue1, #0087ff
	"foreign_link":      tcell.Color92, // xterm:DarkViolet, #8700d7
	"link_number":       tcell.ColorSilver,
	"regular_text":      tcell.ColorWhite,
	"quote_text":        tcell.ColorWhite,
	"preformatted_text": tcell.Color229, // xterm:Wheat1, #ffffaf
	"list_text":         tcell.ColorWhite,
}

func SetColor(key string, color tcell.Color) {
	themeMu.Lock()
	theme[key] = color
	themeMu.Unlock()
}

// GetColor will return tcell.ColorBlack if there is no color for the provided key.
func GetColor(key string) tcell.Color {
	themeMu.RLock()
	defer themeMu.RUnlock()
	return theme[key].TrueColor()
}

// GetColorString returns a string that can be used in a cview color tag,
// for the given theme key.
// It will return "#000000" if there is no color for the provided key.
func GetColorString(key string) string {
	themeMu.RLock()
	defer themeMu.RUnlock()
	color := theme[key].TrueColor()
	if color == tcell.ColorDefault {
		return "-"
	}
	return fmt.Sprintf("#%06x", color.Hex())
}

// GetContrastingColor returns ColorBlack if color is brighter than gray
// otherwise returns ColorWhite if color is dimmer than gray
// if color is ColorDefault (undefined luminance) this returns ColorDefault
func GetContrastingColor(color tcell.Color) tcell.Color {
	if color == tcell.ColorDefault {
		// color should never be tcell.ColorDefault
		// only config keys which end in bg are allowed to be set to default
		// and the only way the argument of this function is set to ColorDefault
		// is if both the text and bg of an element in the UI are set to default
		return tcell.ColorDefault
	}
	r, g, b := color.RGB()
	luminance := (77*r + 150*g + 29*b + 1<<7) >> 8
	const gray = 119 // The middle gray
	if luminance > gray {
		return tcell.ColorBlack
	}
	return tcell.ColorWhite
}

// GetTextColor is the Same as GetColor, unless the key is "default".
// This happens on focus of a UI element which has a bg of default, in which case
// It return tcell.ColorBlack or tcell.ColorWhite, depending on which is more readable
func GetTextColor(key, bg string) tcell.Color {
	themeMu.RLock()
	defer themeMu.RUnlock()
	color := theme[key].TrueColor()
	if color != tcell.ColorDefault {
		return color
	}
	return GetContrastingColor(theme[bg].TrueColor())
}

// GetTextColorString is the Same as GetColorString, unless the key is "default".
// This happens on focus of a UI element which has a bg of default, in which case
// It return tcell.ColorBlack or tcell.ColorWhite, depending on which is more readable
func GetTextColorString(key, bg string) string {
	color := GetTextColor(key, bg)
	return fmt.Sprintf("#%06x", color.Hex())
}