package com.estateunified.panel

import com.google.gson.Gson
import com.google.gson.reflect.TypeToken
import java.nio.charset.StandardCharsets
import java.nio.file.Files
import java.nio.file.Path
import java.util.UUID

internal data class TaskDto(
    val id: String = "task-${UUID.randomUUID().toString().take(8)}",
    val ownerUserId: String,
    val title: String,
    val dueAtIso: String,
    val kind: String = "GENERIC",
    val dealId: String? = null,
    val listingId: String? = null,
    val leadId: String? = null,
    var status: String = "OPEN",
    val note: String = "",
    val createdAtIso: String =
        java.time.format.DateTimeFormatter.ISO_LOCAL_DATE_TIME.format(java.time.LocalDateTime.now()),
    var updatedAtIso: String =
        java.time.format.DateTimeFormatter.ISO_LOCAL_DATE_TIME.format(java.time.LocalDateTime.now()),
)

internal class TasksStore(
    private val gson: Gson,
    private val file: Path,
) {
    private val lock = Any()

    fun listForUser(userId: String): List<TaskDto> =
        synchronized(lock) {
            load().filter { it.ownerUserId == userId }
                .sortedWith(compareBy<TaskDto> { it.status == "DONE" }.thenBy { it.dueAtIso })
        }

    fun add(dto: TaskDto): TaskDto =
        synchronized(lock) {
            val list = load().toMutableList()
            list.add(0, dto)
            persist(list)
            dto
        }

    fun setStatus(id: String, userId: String, status: String): TaskDto? =
        synchronized(lock) {
            val list = load().toMutableList()
            val idx = list.indexOfFirst { it.id == id && it.ownerUserId == userId }
            if (idx < 0) return@synchronized null
            val updated = list[idx].copy(
                status = status,
                updatedAtIso =
                    java.time.format.DateTimeFormatter.ISO_LOCAL_DATE_TIME.format(java.time.LocalDateTime.now()),
            )
            list[idx] = updated
            persist(list)
            updated
        }

    fun delete(id: String, userId: String): Boolean =
        synchronized(lock) {
            val list = load().toMutableList()
            val removed = list.removeIf { it.id == id && it.ownerUserId == userId }
            if (removed) persist(list)
            removed
        }

    private fun load(): MutableList<TaskDto> {
        if (!Files.isRegularFile(file)) return mutableListOf()
        val text = Files.readString(file, StandardCharsets.UTF_8)
        if (text.isBlank()) return mutableListOf()
        return runCatching {
            gson.fromJson<MutableList<TaskDto>>(text, listType) ?: mutableListOf()
        }.getOrElse { mutableListOf() }
    }

    private fun persist(list: List<TaskDto>) {
        Files.createDirectories(file.toAbsolutePath().parent)
        Files.writeString(file, gson.toJson(list), StandardCharsets.UTF_8)
    }

    companion object {
        private val listType = object : TypeToken<MutableList<TaskDto>>() {}.type
    }
}