package com.condado.newsletter.service

import com.condado.newsletter.model.ParsedAiResponse
import io.mockk.every
import io.mockk.mockk
import io.mockk.verify
import org.assertj.core.api.Assertions.assertThat
import org.junit.jupiter.api.Test
import org.junit.jupiter.api.assertThrows
import org.springframework.web.client.RestClient

class AiServiceTest {

    private val mockRestClient: RestClient = mockk()
    private val mockRequestBodyUriSpec: RestClient.RequestBodyUriSpec = mockk()
    private val mockRequestBodySpec: RestClient.RequestBodySpec = mockk()
    private val mockResponseSpec: RestClient.ResponseSpec = mockk()

    private val service = AiService(
        restClient = mockRestClient,
        apiKey = "test-key",
        model = "gpt-4o"
    )

    @Test
    fun should_returnAiResponseText_when_apiCallSucceeds() {
        val rawResponse = "SUBJECT: Test Subject\nBODY:\nTest body content"
        stubRestClient(rawResponse.replace("\n", "\\n"))

        val result = service.generate("My test prompt")

        assertThat(result.subject).isEqualTo("Test Subject")
        assertThat(result.body).isEqualTo("Test body content")
    }

    @Test
    fun should_throwAiServiceException_when_apiReturnsError() {
        every { mockRestClient.post() } throws RuntimeException("API unavailable")

        assertThrows<AiServiceException> {
            service.generate("My prompt")
        }
    }

    @Test
    fun should_extractSubjectAndBody_when_responseIsWellFormatted() {
        val raw = "SUBJECT: Weekly Update\nBODY:\nDear colleagues,\n\nPlease note the snacks."
        val result = service.parseResponse(raw)

        assertThat(result.subject).isEqualTo("Weekly Update")
        assertThat(result.body).isEqualTo("Dear colleagues,\n\nPlease note the snacks.")
    }

    @Test
    fun should_throwParseException_when_responseIsMissingSubjectLine() {
        val raw = "BODY:\nSome body without a subject"

        assertThrows<AiParseException> {
            service.parseResponse(raw)
        }
    }

    @Test
    fun should_throwParseException_when_responseIsMissingBodySection() {
        val raw = "SUBJECT: Some Subject\nNo body section here"

        assertThrows<AiParseException> {
            service.parseResponse(raw)
        }
    }

    // ── helper ──────────────────────────────────────────────────────────────

    private fun stubRestClient(responseText: String) {
        every { mockRestClient.post() } returns mockRequestBodyUriSpec
        every { mockRequestBodyUriSpec.uri(any<String>()) } returns mockRequestBodySpec
        every { mockRequestBodySpec.header(any(), any()) } returns mockRequestBodySpec
        every { mockRequestBodySpec.body(any<Any>()) } returns mockRequestBodySpec
        every { mockRequestBodySpec.retrieve() } returns mockResponseSpec
        every { mockResponseSpec.body(String::class.java) } returns """
            {
              "choices": [
                { "message": { "content": "$responseText" } }
              ]
            }
        """.trimIndent()
    }
}