/*
 * Copyright (C) 2025 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.android.eyedroppertester.ui

import androidx.compose.foundation.BorderStroke
import androidx.compose.foundation.Image
import androidx.compose.foundation.background
import androidx.compose.foundation.border
import androidx.compose.foundation.layout.Arrangement
import androidx.compose.foundation.layout.Box
import androidx.compose.foundation.layout.Column
import androidx.compose.foundation.layout.Row
import androidx.compose.foundation.layout.Spacer
import androidx.compose.foundation.layout.fillMaxSize
import androidx.compose.foundation.layout.fillMaxWidth
import androidx.compose.foundation.layout.height
import androidx.compose.foundation.layout.padding
import androidx.compose.foundation.layout.size
import androidx.compose.material3.Button
import androidx.compose.material3.Text
import androidx.compose.runtime.Composable
import androidx.compose.ui.Alignment
import androidx.compose.ui.Modifier
import androidx.compose.ui.graphics.Color
import androidx.compose.ui.layout.ContentScale
import androidx.compose.ui.res.painterResource
import androidx.compose.ui.res.stringResource
import androidx.compose.ui.unit.dp
import androidx.compose.ui.unit.sp
import com.android.eyedroppertester.R

/**
 * Primary composable that builds the main UI with a button, background image, and received color.
 * Only reads the current color state; state management is otherwise hoisted up to MainActivity.
 */
@Composable
fun LaunchEyeDropperScreen(
    uiColorState: ColorState,
    onClick: () -> Unit,
) {
    // Container box for whole UI
    Box(modifier = Modifier.fillMaxSize()) {
        // (1) Colorful background image that we will select colors from
        Image(
            painter = painterResource(id = R.drawable.parrot_stock_image),
            contentDescription = "background_image",
            modifier = Modifier.fillMaxSize(),
            contentScale = ContentScale.Crop
        )
        // (2) All other UI elements on top
        Column(
            modifier = Modifier
                .fillMaxSize()
                .padding(16.dp),
            horizontalAlignment = Alignment.CenterHorizontally,
            verticalArrangement = Arrangement.Center
        ) {
            // (2a) Title of application
            Text(
                text = stringResource(R.string.app_name),
                color = Color.White,
                fontSize = 48.sp
            )
            Spacer(modifier = Modifier.height(32.dp))

            // (2b) "Launch EyeDropper" button to start EyeDropper activity
            Button(
                modifier = Modifier.fillMaxWidth(0.25f),
                onClick = onClick
            ) {
                Text(
                    text = stringResource(R.string.button_label),
                    fontSize = 16.sp
                )
            }
            Spacer(modifier = Modifier.height(16.dp))

            // (2c) Beneath the button, display the hex of the received result.
            Row(
                verticalAlignment = Alignment.CenterVertically
            ) {
                Text(
                    text = stringResource(R.string.received_color),
                    color = Color.White,
                    fontSize = 32.sp,
                )
                Text(
                    text = uiColorState.currentColorHex,
                    color = Color(uiColorState.currentColor),
                    fontSize = 32.sp,
                )
            }
            Spacer(modifier = Modifier.height(16.dp))

            // (2d) Also display color of the received result in small square.
            Box(
                modifier = Modifier
                    .size(64.dp)
                    .background(color = Color(uiColorState.currentColor))
                    .border(BorderStroke(4.dp, Color.White))
            )
        }
    }
}