package conversion

import (
	"context"
	"encoding/json"
	"io"
	"strings"
	"testing"
	"time"

	"github.com/stretchr/testify/assert"
	"github.com/stretchr/testify/require"
)

// noopService 是一個 compile-time 驗證 — 用來確認 Service interface 的方法集合穩定。
// 真實實作（Flow）會在 T6 補。這裡只測 interface 簽名沒有打錯（避免 T6 才發現要改 interface）。
type noopService struct{}

func (noopService) InitJob(ctx context.Context, in InitJobInput) (*Job, error) {
	return nil, nil
}

func (noopService) GetJob(ctx context.Context, userID, jobID string) (*Job, error) {
	return nil, nil
}

func (noopService) PromoteToModels(ctx context.Context, userID, jobID, name string) (*PromoteResult, error) {
	return nil, nil
}

// Phase 0.8b T4：DownloadRedirectURL 改 DownloadStream（API key 模式下沒有 delegated token，
// 改 server-side stream proxy；對應 ADR-015 §7 / conversion.md §4.1）
func (noopService) DownloadStream(ctx context.Context, userID, jobID string) (io.ReadCloser, *DownloadMetadata, error) {
	return nil, nil, nil
}

func (noopService) ActiveJob(ctx context.Context, userID string) (*Job, error) {
	return nil, nil
}

// File-scope compile-time check — 若 Service interface 改變，
// noopService 就不再實作此 interface，編譯失敗。
// 移到 file scope（T1 review M1）：t.Run 內的 var declaration 只在執行該 test 時驗，
// 而我們希望「package 編譯成功」就保證 interface 穩定。
var _ Service = noopService{}

// TestService_InterfaceSatisfied 在 test 中再 assert 一次，作為文件性說明。
func TestService_InterfaceSatisfied(t *testing.T) {
	t.Parallel()
	var _ Service = noopService{}
}

// TestJob_JSONShape 驗證 Job struct 的 JSON tag 與 api-conversion.md §1-2 response 對齊。
//
// 這是契約測試：frontend 依 api-conversion.md 寫 type；backend 改 json tag 一定要回頭看這個 test。
func TestJob_JSONShape(t *testing.T) {
	t.Parallel()

	createdAt, _ := time.Parse(time.RFC3339, "2026-04-30T12:00:00Z")
	expiresAt := createdAt.Add(7 * 24 * time.Hour)
	job := Job{
		JobID:          "550e8400-e29b-41d4-a716-446655440000",
		Status:         "running",
		Stage:          "bie",
		Progress:       45,
		StageProgress:  60,
		CreatedAt:      createdAt,
		UpdatedAt:      createdAt.Add(5 * time.Minute),
		ExpiresAt:      expiresAt,
		SourceFilename: "yolov5s.onnx",
		TargetChip:     "720",
	}

	raw, err := json.Marshal(job)
	require.NoError(t, err)

	// 必要欄位都在
	assert.Contains(t, string(raw), `"job_id":"550e8400-e29b-41d4-a716-446655440000"`)
	assert.Contains(t, string(raw), `"status":"running"`)
	assert.Contains(t, string(raw), `"stage":"bie"`)
	assert.Contains(t, string(raw), `"progress":45`)
	assert.Contains(t, string(raw), `"stage_progress":60`)
	assert.Contains(t, string(raw), `"created_at":"2026-04-30T12:00:00Z"`)
	assert.Contains(t, string(raw), `"expires_at":"2026-05-07T12:00:00Z"`)
	assert.Contains(t, string(raw), `"source_filename":"yolov5s.onnx"`)
	assert.Contains(t, string(raw), `"target_chip":"720"`)

	// error 欄位 zero value 時應被 omitempty 隱藏
	assert.NotContains(t, string(raw), `"error_code"`)
	assert.NotContains(t, string(raw), `"error_message"`)
}

// TestJob_FailedShape 驗證 failed job 的 error 欄位序列化。
func TestJob_FailedShape(t *testing.T) {
	t.Parallel()

	job := Job{
		JobID:        "job-failed",
		Status:       "failed",
		ErrorCode:    "QUANTIZATION_FAILED",
		ErrorMessage: "model has unsupported operator",
	}
	raw, err := json.Marshal(job)
	require.NoError(t, err)

	assert.Contains(t, string(raw), `"error_code":"QUANTIZATION_FAILED"`)
	assert.Contains(t, string(raw), `"error_message":"model has unsupported operator"`)
}

// TestPromoteResult_JSONShape 對齊 api-conversion.md §3 response。
func TestPromoteResult_JSONShape(t *testing.T) {
	t.Parallel()

	createdAt, _ := time.Parse(time.RFC3339, "2026-04-30T12:30:00Z")
	pr := PromoteResult{
		ModelID:     "abc-123",
		Source:      "converted",
		SourceJobID: "550e8400-...",
		Name:        "YOLOv5 Face KL520",
		TargetChip:  "kl520",
		FileSize:    12345678,
		Status:      "ready",
		CreatedAt:   createdAt,
	}

	raw, err := json.Marshal(pr)
	require.NoError(t, err)

	assert.Contains(t, string(raw), `"model_id":"abc-123"`)
	assert.Contains(t, string(raw), `"source":"converted"`)
	assert.Contains(t, string(raw), `"source_job_id":"550e8400-..."`)
	assert.Contains(t, string(raw), `"file_size":12345678`)
	assert.Contains(t, string(raw), `"status":"ready"`)
	assert.Contains(t, string(raw), `"target_chip":"kl520"`)
}

// TestInitJobInput_AcceptsReader 驗證 InitJobInput.Body 接受 io.Reader（即 streaming 不收 buffer）。
//
// 關鍵：若有人不小心把欄位改成 []byte，這個測試編譯會壞。
func TestInitJobInput_AcceptsReader(t *testing.T) {
	t.Parallel()

	in := InitJobInput{
		UserID:        "user-abc",
		ContentType:   "multipart/form-data; boundary=xyz",
		Body:          strings.NewReader("--xyz--"),
		ContentLength: 7,
	}

	// 確認 Body 是 io.Reader（compile time 透過 type assertion）
	var _ io.Reader = in.Body
	assert.Equal(t, "user-abc", in.UserID)
}