package com.peachpasswords.autofill

import android.app.assist.AssistStructure
import android.text.InputType
import android.view.View
import android.view.autofill.AutofillId

enum class AutofillOriginTrust { TRUSTED_WEB, TRUSTED_NATIVE, UNKNOWN }

/**
 * The autofillable fields discovered in one [AssistStructure], plus the origin
 * Android authenticated for ranking vault entries.
 */
data class ParsedStructure(
    val usernameId: AutofillId? = null,
    val emailId: AutofillId? = null,
    val passwordId: AutofillId? = null,
    val otpId: AutofillId? = null,
    val usernameValue: String? = null,
    val emailValue: String? = null,
    val passwordValue: String? = null,
    val otpValue: String? = null,
    val webDomain: String? = null,
    val packageName: String? = null,
    val originTrust: AutofillOriginTrust = AutofillOriginTrust.UNKNOWN,
    val verifiedDomains: List<String> = emptyList(),
) {
    /** The id we put the account identifier into — email preferred, else username. */
    val identityId: AutofillId? get() = emailId ?: usernameId
    val hasUsableField: Boolean get() = passwordId != null || identityId != null || otpId != null
    /** Best label to rank entries against. */
    val origin: String? get() = webDomain ?: packageName
}

/**
 * Walks an [AssistStructure] to classify username/email/password/OTP fields.
 * Mirrors the browser content-script's field detection: trust explicit autofill
 * hints first, then fall back to input-type and id/hint keyword heuristics so
 * unannotated login forms still work.
 */
object AssistStructureParser {

    fun parse(structure: AssistStructure): ParsedStructure {
        // View-node package ids are supplied by the foreground app; the framework-owned
        // activity component is the authenticated caller identity.
        var result = ParsedStructure(packageName = structure.activityComponent?.packageName)
        val windows = structure.windowNodeCount
        for (i in 0 until windows) {
            val root = structure.getWindowNodeAt(i).rootViewNode
            result = traverse(root, result)
        }
        return result
    }

    private fun traverse(node: AssistStructure.ViewNode, acc: ParsedStructure): ParsedStructure {
        var result = acc
        if (result.webDomain == null && !node.webDomain.isNullOrBlank()) {
            result = result.copy(webDomain = node.webDomain)
        }

        val id = node.autofillId
        if (id != null && isFillable(node)) {
            val value = node.autofillValue?.takeIf { it.isText }?.textValue?.toString()
                ?: node.text?.toString()
            result = when (classify(node)) {
                FieldKind.PASSWORD -> if (result.passwordId == null) result.copy(passwordId = id, passwordValue = value) else result
                FieldKind.USERNAME -> if (result.usernameId == null) result.copy(usernameId = id, usernameValue = value) else result
                FieldKind.EMAIL -> if (result.emailId == null) result.copy(emailId = id, emailValue = value) else result
                FieldKind.OTP -> if (result.otpId == null) result.copy(otpId = id, otpValue = value) else result
                FieldKind.NONE -> result
            }
        }

        for (i in 0 until node.childCount) {
            result = traverse(node.getChildAt(i), result)
        }
        return result
    }

    private fun isFillable(node: AssistStructure.ViewNode): Boolean =
        node.autofillType == View.AUTOFILL_TYPE_TEXT &&
            node.visibility == View.VISIBLE

    private enum class FieldKind { USERNAME, EMAIL, PASSWORD, OTP, NONE }

    private fun classify(node: AssistStructure.ViewNode): FieldKind {
        node.autofillHints?.forEach { hint ->
            when (hint.lowercase()) {
                View.AUTOFILL_HINT_PASSWORD, "password" -> return FieldKind.PASSWORD
                View.AUTOFILL_HINT_USERNAME, "username" -> return FieldKind.USERNAME
                View.AUTOFILL_HINT_EMAIL_ADDRESS, "email", "emailaddress" -> return FieldKind.EMAIL
                "otp", "smsotpcode", "2facode" -> return FieldKind.OTP
            }
        }

        val type = node.inputType
        val isPasswordType = type and InputType.TYPE_MASK_VARIATION == InputType.TYPE_TEXT_VARIATION_PASSWORD ||
            type and InputType.TYPE_MASK_VARIATION == InputType.TYPE_TEXT_VARIATION_WEB_PASSWORD ||
            type and InputType.TYPE_MASK_VARIATION == InputType.TYPE_NUMBER_VARIATION_PASSWORD
        if (isPasswordType) return FieldKind.PASSWORD

        val haystack = listOfNotNull(node.idEntry, node.hint, node.text?.toString())
            .joinToString(" ").lowercase()
        return when {
            haystack.isBlank() -> FieldKind.NONE
            Regex("\\b(otp|2fa|mfa|one[- ]?time|verification code|auth code)\\b").containsMatchIn(haystack) -> FieldKind.OTP
            haystack.contains("password") || haystack.contains("passwd") || haystack.contains("pwd") -> FieldKind.PASSWORD
            haystack.contains("email") || haystack.contains("e-mail") -> FieldKind.EMAIL
            haystack.contains("user") || haystack.contains("login") || haystack.contains("account") -> FieldKind.USERNAME
            else -> FieldKind.NONE
        }
    }
}