package com.android.trisolarisserver.component.geo

import com.fasterxml.jackson.databind.JsonNode
import com.fasterxml.jackson.databind.ObjectMapper
import org.slf4j.LoggerFactory
import org.springframework.http.HttpEntity
import org.springframework.http.HttpHeaders
import org.springframework.http.HttpMethod
import org.springframework.beans.factory.annotation.Value
import org.springframework.stereotype.Component
import org.springframework.web.client.RestTemplate
import org.springframework.web.util.UriComponentsBuilder

@Component
class PostalPincodeClient(
    private val restTemplate: RestTemplate,
    private val objectMapper: ObjectMapper,
    @Value("\${pincode.postal.baseUrl:https://api.postalpincode.in}")
    private val baseUrl: String
) {
    private val logger = LoggerFactory.getLogger(PostalPincodeClient::class.java)

    fun resolve(pinCode: String): PincodeLookupResult {
        val first = fetch(baseUrl, pinCode)
        if (first.resolvedCityState != null) return first
        if (first.status == "ERROR" && baseUrl.startsWith("https://")) {
            val httpUrl = baseUrl.replaceFirst("https://", "http://")
            val second = fetch(httpUrl, pinCode)
            if (second.resolvedCityState != null) return second
            return second
        }
        return first
    }

    private fun fetch(base: String, pinCode: String): PincodeLookupResult {
        val url = UriComponentsBuilder.fromUriString(base)
            .path("/pincode/{pin}")
            .buildAndExpand(pinCode)
            .toUriString()
        val headers = HttpHeaders().apply {
            set("User-Agent", "Mozilla/5.0 (TrisolarisServer)")
            set("Accept", "application/json")
            set("Connection", "close")
        }
        val entity = HttpEntity<Unit>(headers)
        var lastError: Exception? = null
        repeat(2) {
            try {
                val response = restTemplate.exchange(url, HttpMethod.GET, entity, String::class.java)
                val body = response.body ?: return PincodeLookupResult(null, null, "EMPTY_BODY", "postalpincode.in", requestUrl = url)
                val resolved = parseCityState(body)
                val status = if (resolved == null) "ZERO_RESULTS" else "OK"
                return PincodeLookupResult(resolved, body, status, "postalpincode.in", requestUrl = url)
            } catch (ex: Exception) {
                lastError = ex
                try {
                    Thread.sleep(200)
                } catch (_: InterruptedException) {
                    Thread.currentThread().interrupt()
                }
            }
        }
        val errorMessage = lastError?.message
        if (errorMessage != null) {
            logger.warn("Postalpincode lookup failed: {}", errorMessage)
        }
        return PincodeLookupResult(null, null, "ERROR", "postalpincode.in", errorMessage, url)
    }

    private fun parseCityState(body: String): String? {
        val root = objectMapper.readTree(body)
        if (!root.isArray || root.isEmpty) return null
        val first = root.first()
        val status = first.path("Status").asText(null)
        if (!status.equals("Success", true)) return null
        val offices = first.path("PostOffice")
        if (!offices.isArray || offices.isEmpty) return null
        val office = chooseOffice(offices) ?: return null
        val district = office.path("District").asText(null)
        val state = office.path("State").asText(null)
        if (district.isNullOrBlank() && state.isNullOrBlank()) return null
        return listOfNotNull(district?.ifBlank { null }, state?.ifBlank { null }).joinToString(", ")
    }

    private fun chooseOffice(offices: JsonNode): JsonNode? {
        val delivery = offices.firstOrNull { it.path("DeliveryStatus").asText("").equals("Delivery", true) }
        return delivery ?: offices.firstOrNull()
    }
}