package com.android.systemui.biometrics.ui.viewmodel

import android.content.Context
import android.graphics.drawable.Drawable
import android.hardware.biometrics.Flags.customBiometricPrompt
import android.hardware.biometrics.PromptContentView
import android.text.InputType
import com.android.internal.widget.LockPatternView
import com.android.systemui.Flags.constraintBp
import com.android.systemui.biometrics.Utils
import com.android.systemui.biometrics.domain.interactor.CredentialStatus
import com.android.systemui.biometrics.domain.interactor.PromptCredentialInteractor
import com.android.systemui.biometrics.domain.model.BiometricPromptRequest
import com.android.systemui.biometrics.shared.model.BiometricUserInfo
import com.android.systemui.dagger.qualifiers.Application
import com.android.systemui.res.R
import javax.inject.Inject
import kotlin.reflect.KClass
import kotlinx.coroutines.flow.Flow
import kotlinx.coroutines.flow.MutableSharedFlow
import kotlinx.coroutines.flow.MutableStateFlow
import kotlinx.coroutines.flow.asSharedFlow
import kotlinx.coroutines.flow.asStateFlow
import kotlinx.coroutines.flow.combine
import kotlinx.coroutines.flow.filterIsInstance
import kotlinx.coroutines.flow.map

/** View-model for all CredentialViews within BiometricPrompt. */
class CredentialViewModel
@Inject
constructor(
    @Application private val applicationContext: Context,
    private val credentialInteractor: PromptCredentialInteractor,
) {

    /** Top level information about the prompt. */
    val header: Flow<CredentialHeaderViewModel> =
        combine(
            credentialInteractor.prompt.filterIsInstance<BiometricPromptRequest.Credential>(),
            credentialInteractor.showTitleOnly
        ) { request, showTitleOnly ->
            val flagEnabled = customBiometricPrompt() && constraintBp()
            val showTitleOnlyForCredential = showTitleOnly && flagEnabled
            BiometricPromptHeaderViewModelImpl(
                request,
                user = request.userInfo,
                title = request.title,
                subtitle = if (showTitleOnlyForCredential) "" else request.subtitle,
                contentView =
                    if (flagEnabled && !showTitleOnlyForCredential) request.contentView else null,
                description =
                    if (flagEnabled && request.contentView != null) "" else request.description,
                icon = applicationContext.asLockIcon(request.userInfo.deviceCredentialOwnerId),
                showEmergencyCallButton = request.showEmergencyCallButton
            )
        }

    /** Input flags for text based credential views */
    val inputFlags: Flow<Int?> =
        credentialInteractor.prompt.map {
            when (it) {
                is BiometricPromptRequest.Credential.Pin ->
                    InputType.TYPE_CLASS_NUMBER or InputType.TYPE_NUMBER_VARIATION_PASSWORD
                else -> null
            }
        }

    /** If stealth mode is active (hide user credential input). */
    val stealthMode: Flow<Boolean> =
        credentialInteractor.prompt.map {
            when (it) {
                is BiometricPromptRequest.Credential.Pattern -> it.stealthMode
                else -> false
            }
        }

    private val _animateContents: MutableStateFlow<Boolean> = MutableStateFlow(true)
    /** If this view should be animated on transitions. */
    val animateContents = _animateContents.asStateFlow()

    /** Error messages to show the user. */
    val errorMessage: Flow<String> =
        combine(credentialInteractor.verificationError, credentialInteractor.prompt) { error, p ->
            when (error) {
                is CredentialStatus.Fail.Error -> error.error
                        ?: applicationContext.asBadCredentialErrorMessage(p)
                is CredentialStatus.Fail.Throttled -> error.error
                null -> ""
            }
        }

    private val _validatedAttestation: MutableSharedFlow<ByteArray?> = MutableSharedFlow()
    /** Results of [checkPatternCredential]. A non-null attestation is supplied on success. */
    val validatedAttestation: Flow<ByteArray?> = _validatedAttestation.asSharedFlow()

    private val _remainingAttempts: MutableStateFlow<RemainingAttempts> =
        MutableStateFlow(RemainingAttempts())
    /** If set, the number of remaining attempts before the user must stop. */
    val remainingAttempts: Flow<RemainingAttempts> = _remainingAttempts.asStateFlow()

    /** Enable transition animations. */
    fun setAnimateContents(animate: Boolean) {
        _animateContents.value = animate
    }

    /** Show an error message to inform the user the pattern is too short to attempt validation. */
    fun showPatternTooShortError() {
        credentialInteractor.setVerificationError(
            CredentialStatus.Fail.Error(
                applicationContext.asBadCredentialErrorMessage(
                    BiometricPromptRequest.Credential.Pattern::class
                )
            )
        )
    }

    /** Reset the error message to an empty string. */
    fun resetErrorMessage() {
        credentialInteractor.resetVerificationError()
    }

    /** Check a PIN or password and update [validatedAttestation] or [remainingAttempts]. */
    suspend fun checkCredential(text: CharSequence, header: CredentialHeaderViewModel) =
        checkCredential(credentialInteractor.checkCredential(header.asRequest(), text = text))

    /** Check a pattern and update [validatedAttestation] or [remainingAttempts]. */
    suspend fun checkCredential(
        pattern: List<LockPatternView.Cell>,
        header: CredentialHeaderViewModel
    ) = checkCredential(credentialInteractor.checkCredential(header.asRequest(), pattern = pattern))

    private suspend fun checkCredential(result: CredentialStatus) {
        when (result) {
            is CredentialStatus.Success.Verified -> {
                _validatedAttestation.emit(result.hat)
                _remainingAttempts.value = RemainingAttempts()
            }
            is CredentialStatus.Fail.Error -> {
                _validatedAttestation.emit(null)
                _remainingAttempts.value =
                    RemainingAttempts(result.remainingAttempts, result.urgentMessage ?: "")
            }
            is CredentialStatus.Fail.Throttled -> {
                // required for completeness, but a throttled error cannot be the final result
                _validatedAttestation.emit(null)
                _remainingAttempts.value = RemainingAttempts()
            }
        }
    }

    fun doEmergencyCall(context: Context) {
        val intent =
            context
                .getSystemService(android.telecom.TelecomManager::class.java)!!
                .createLaunchEmergencyDialerIntent(null)
                .setFlags(
                    android.content.Intent.FLAG_ACTIVITY_NEW_TASK or
                        android.content.Intent.FLAG_ACTIVITY_CLEAR_TOP
                )
        context.startActivity(intent)
    }
}

private fun Context.asBadCredentialErrorMessage(prompt: BiometricPromptRequest?): String =
    asBadCredentialErrorMessage(
        if (prompt != null) prompt::class else BiometricPromptRequest.Credential.Password::class
    )

private fun <T : BiometricPromptRequest> Context.asBadCredentialErrorMessage(
    clazz: KClass<T>
): String =
    getString(
        when (clazz) {
            BiometricPromptRequest.Credential.Pin::class -> R.string.biometric_dialog_wrong_pin
            BiometricPromptRequest.Credential.Password::class ->
                R.string.biometric_dialog_wrong_password
            BiometricPromptRequest.Credential.Pattern::class ->
                R.string.biometric_dialog_wrong_pattern
            else -> R.string.biometric_dialog_wrong_password
        }
    )

private fun Context.asLockIcon(userId: Int): Drawable {
    val id =
        if (Utils.isManagedProfile(this, userId)) {
            R.drawable.auth_dialog_enterprise
        } else {
            R.drawable.auth_dialog_lock
        }
    return resources.getDrawable(id, theme)
}

private class BiometricPromptHeaderViewModelImpl(
    val request: BiometricPromptRequest.Credential,
    override val user: BiometricUserInfo,
    override val title: String,
    override val subtitle: String,
    override val description: String,
    override val contentView: PromptContentView?,
    override val icon: Drawable,
    override val showEmergencyCallButton: Boolean,
) : CredentialHeaderViewModel

private fun CredentialHeaderViewModel.asRequest(): BiometricPromptRequest.Credential =
    (this as BiometricPromptHeaderViewModelImpl).request