/*
 * Miscellaneous utility stuff.
 */
package name.blackcap.exifwasher

import java.awt.Component
import java.awt.Cursor
import java.awt.Toolkit
import javax.swing.*
import kotlin.annotation.*
import kotlin.properties.ReadWriteProperty
import kotlin.reflect.*

/**
 * Delegate that makes a var that can only be set once. This is commonly
 * needed in Swing, because some vars inevitably need to be declared at
 * outer levels but initialized in the Swing event dispatch thread.
 */
class SetOnce<T: Any>: ReadWriteProperty<Any?,T> {
    private var setOnceValue: T? = null

    override operator fun getValue(thisRef: Any?, property: KProperty<*>): T {
        if (setOnceValue == null) {
            throw RuntimeException("${property.name} has not been initialized")
        } else {
            return setOnceValue!!
        }
    }

    @Synchronized
    override operator fun setValue(thisRef: Any?, property: KProperty<*>, value: T): Unit {
        if (setOnceValue != null) {
            throw RuntimeException("${property.name} has already been initialized")
        }
        setOnceValue = value
    }
}

/**
 * Run something in the Swing thread, asynchronously.
 * @param block lambda containing code to run
 */
fun inSwingThread(block: () -> Unit) {
    SwingUtilities.invokeLater(Runnable(block))
}

/**
 * Run something in the Swing thread, synchronously.
 * @param block lambda containing code to run
 */
fun inSynSwingThread(block: () -> Unit) {
    SwingUtilities.invokeAndWait(Runnable(block))
}

/**
 * Make a shortcut for a menu item, using the standard combining key
 * (control, command, etc.) for the system we're on.
 * @param key KeyEvent constant describing the key
 */
fun JMenuItem.makeShortcut(key: Int): Unit {
    val SC_KEY_MASK = Toolkit.getDefaultToolkit().menuShortcutKeyMask
    setAccelerator(KeyStroke.getKeyStroke(key, SC_KEY_MASK))
}

/**
 * Given a MenuElement object, get the item whose text matches the
 * specified text.
 * @param text to match
 * @return first matched element, null if no match found
 */
fun MenuElement.getItem(name: String) : JMenuItem? {
    subElements.forEach {
        val jMenuItem = it.component as? JMenuItem
        if (jMenuItem?.text == name) {
            return jMenuItem
        }
    }
    return null
}

/**
 * Change to the standard wait cursor.
 */
fun Component.useWaitCursor() {
    this.cursor = Cursor.getPredefinedCursor(Cursor.WAIT_CURSOR)
}

/**
 * Return back to the normal cursor().
 */
fun Component.useNormalCursor() {
    this.cursor = Cursor.getDefaultCursor()
}

/**
 * Thrown if the programmer botches something in our DSL.
 */
class SwingWorkerException(message: String): Exception(message) { }

/**
 * A simplified SwingWorker DSL. It does not support intermediate
 * results. Just lets one define a background task and something
 * to execute when complete.
 *
 * @param T Type returned by inBackground (Java doInBackground) task.
 */
class SwingWorkerBuilder<T>: SwingWorker<T,Unit>() {
    private var inBackgroundLambda: (SwingWorkerBuilder<T>.() -> T)? = null
    private var whenDoneLambda: (SwingWorkerBuilder<T>.() -> Unit)? = null

    private fun <U> setOnce(prop: KMutableProperty0<(SwingWorkerBuilder<T>.() -> U)?>, value: SwingWorkerBuilder<T>.() -> U) {
        if (prop.get() != null) {
            throw SwingWorkerException(prop.name.removeSuffix("Lambda") + " already defined!")
        }
        prop.set(value)
    }

    /**
     * Define the inBackground task.
     */
    fun inBackground(lambda: SwingWorkerBuilder<T>.() -> T): Unit {
        setOnce<T>(::inBackgroundLambda, lambda)
    }

    /**
     * Define the whenDone task.
     */
    fun whenDone(lambda: SwingWorkerBuilder<T>.() -> Unit): Unit {
        setOnce<Unit>(::whenDoneLambda, lambda)
    }

    /**
     * Validates we've been properly initialized.
     */
    fun validate(): Unit {
        if (inBackgroundLambda == null) {
            throw SwingWorkerException("inBackground not defined!")
        }
    }

    /* standard overrides for SwingWorker follow */

    override fun doInBackground(): T = inBackgroundLambda!!.invoke(this)

    override fun done(): Unit = whenDoneLambda?.invoke(this) ?: Unit
}

/**
 * Provides for an outer swingWorker block to contain the DSL.
 */
fun <T> swingWorker(initializer: SwingWorkerBuilder<T>.() -> Unit): Unit {
    SwingWorkerBuilder<T>().run {
        initializer()
        validate()
        execute()
    }
}

/**
 * Close a dialog (don't just hide it).
 */
fun JDialog.close() {
    setVisible(false)
    dispose()
}