package com.suno.android.extensions

import androidx.compose.ui.graphics.Color

private const val THREE_DIGIT_HEX = 3
private const val SIX_DIGIT_HEX = 6
private const val EIGHT_DIGIT_HEX = 8
private const val HEX_RADIX = 16

/**
 * Converts a string representation of a color to a Compose Color object.
 *
 * Supported formats:
 * - 6-digit hex: "FF5733" or "#FF5733"
 * - 8-digit hex with alpha: "FF5733AA" or "#FF5733AA" (alpha repositioned from end to start)
 * - 3-digit hex shorthand: "F73" or "#F73" (expanded to "FF7733")
 * - Keywords (case-sensitive): { transparent }
 *
 * @return Compose Color object if valid web hex color code, otherwise null.
 */
fun String.xAsColor(): Color? {
    // Handle special keywords (case-sensitive)
    if (this.equals("transparent", ignoreCase = false)) {
        return Color.Transparent
    }

    return try {
        parseHexColor(this)
    } catch (_: NumberFormatException) {
        null
    } catch (_: IllegalArgumentException) {
        null
    }
}

/**
 * Parses a hex color string and returns a Compose Color object.
 * Expects normalized hex format validation to happen in the caller.
 */
private fun parseHexColor(
    hexString: String,
): Color? {
    val normalized = hexString.trim().uppercase().removePrefix("#")

    // Validate that all characters are valid hex digits
    if (!normalized.all { it in '0'..'9' || it in 'A'..'F' }) {
        return null
    }

    // Parse based on length and convert to ARGB Int format
    val argbInt = when (normalized.length) {
        THREE_DIGIT_HEX -> {
            // Expand shorthand: "F73" -> "FF7733"
            val expanded = normalized.map { "$it$it" }.joinToString("")
            // 6-digit hex gets full opacity (0xFF prefix for alpha)
            "FF$expanded".toULong(HEX_RADIX).toInt()
        }
        SIX_DIGIT_HEX -> {
            // 6-digit hex gets full opacity (0xFF prefix for alpha)
            "FF$normalized".toULong(HEX_RADIX).toInt()
        }
        EIGHT_DIGIT_HEX -> {
            // Backend sends alpha at the end of the string in web format (RRGGBBAA)
            // Android Color(Int) expects alpha at the front (AARRGGBB)
            val alpha = normalized.substring(SIX_DIGIT_HEX, EIGHT_DIGIT_HEX)
            val rgb = normalized.substring(0, SIX_DIGIT_HEX)
            "$alpha$rgb".toULong(HEX_RADIX).toInt()
        }
        else -> null
    }
    return argbInt?.let { Color(it) }
}