package com.peachpasswords.passkeys

import com.peachpasswords.vault.VaultEntry
import kotlinx.serialization.json.Json
import kotlinx.serialization.json.contentOrNull
import kotlinx.serialization.json.jsonArray
import kotlinx.serialization.json.jsonObject
import kotlinx.serialization.json.jsonPrimitive

data class PasskeyCredentialCandidate(
    val entryId: String,
    val title: String,
    val rpId: String,
    val credentialId: String,
    val username: String,
    val displayName: String,
    val lastUsedAt: Long?,
)

object PasskeyCredentialPlanner {
    private val json = Json { ignoreUnknownKeys = true }

    fun candidates(entries: List<VaultEntry>, requestJson: String): List<PasskeyCredentialCandidate> {
        val request = runCatching { json.parseToJsonElement(requestJson).jsonObject }.getOrNull() ?: return emptyList()
        val requestedRpId = request["rpId"]?.jsonPrimitive?.contentOrNull?.trim()?.lowercase() ?: return emptyList()
        val allowedIds = runCatching { request["allowCredentials"]?.jsonArray }.getOrNull()
            ?.mapNotNull { item ->
                runCatching { item.jsonObject["id"]?.jsonPrimitive?.contentOrNull }.getOrNull()
            }
            ?.filter { it.isNotBlank() }
            ?.toSet()

        return entries.asSequence()
            .filter { it.deletedAt == null && it.passkey != null }
            .mapNotNull { entry ->
                val passkey = entry.passkey ?: return@mapNotNull null
                val rpId = passkey.rpId.trim().lowercase()
                val credentialId = passkey.credentialId
                if (rpId != requestedRpId) return@mapNotNull null
                if (!allowedIds.isNullOrEmpty() && credentialId !in allowedIds) return@mapNotNull null
                val username = passkey.userName.ifBlank { entry.username ?: entry.email ?: entry.title }
                PasskeyCredentialCandidate(
                    entryId = entry.id,
                    title = entry.title,
                    rpId = passkey.rpId,
                    credentialId = credentialId,
                    username = username,
                    displayName = passkey.userDisplayName?.takeIf { it.isNotBlank() } ?: entry.title,
                    lastUsedAt = entry.lastUsedAt,
                )
            }
            .sortedWith(
                compareByDescending<PasskeyCredentialCandidate> { it.lastUsedAt ?: Long.MIN_VALUE }
                    .thenBy { it.displayName.lowercase() }
                    .thenBy { it.username.lowercase() },
            )
            .toList()
    }
}