package handlers

// device_inference_options_test.go — M4：POST /api/devices/:id/inference/options
// 的 HTTP 契約測試（推論期切換解析方式 / label 表）。
//
// 測試分兩層：
//
//  1. parseInferenceOptionsRequest — 這裡是本 endpoint 幾乎全部的邏輯
//     （JSON / multipart 解析、值域驗證、大小上限、nil vs 空陣列的語意）。
//     它只依賴 *gin.Context，可以完整單元測試。
//  2. SetInferenceOptions handler — 只驗它自己負責的分支：device 不存在、
//     driver 不支援、driver 回錯。
//
// ⚠️ 測試接縫限制（與 device_flash_tasktype_test.go 同一個既有問題）：
// DeviceHandler.deviceMgr 是具體的 *device.Manager，其 sessions map 未匯出、
// 只能由真實硬體填入，跨 package 無法注入 fake session。因此「成功路徑打到
// driver」這段沒有 handler 級測試 —— 由 buildSetInferenceOptionsCommand 的
// 單元測試（driver/kneron）與實機驗收覆蓋。這是既有架構限制，不是本次引入。

import (
	"bytes"
	"encoding/json"
	"fmt"
	"mime/multipart"
	"net/http"
	"net/http/httptest"
	"strings"
	"testing"

	"visiona-local/server/internal/device"
	"visiona-local/server/internal/driver"
	"visiona-local/server/internal/driver/kneron"
	"visiona-local/server/internal/labelfile"

	"github.com/gin-gonic/gin"
)

// ── helpers ──────────────────────────────────────────────────────────

// errorCode 取出統一錯誤格式裡的 error.code。
//
// 原先住在 device_flash_tasktype_test.go；該檔隨「燒錄時選推論種類」功能一起
// 移除後搬來這裡（本檔是目前唯一的使用者）。
func errorCode(parsed map[string]interface{}) string {
	errObj, ok := parsed["error"].(map[string]interface{})
	if !ok {
		return ""
	}
	code, _ := errObj["code"].(string)
	return code
}

// runParse 以指定的 body / content-type 呼叫 parseInferenceOptionsRequest。
func runParse(t *testing.T, contentType string, body []byte) (driver.InferenceOptions, labelSummary, *apiError) {
	t.Helper()

	var (
		opts    driver.InferenceOptions
		summary labelSummary
		apiErr  *apiError
	)

	router := gin.New()
	router.POST("/x", func(c *gin.Context) {
		opts, summary, apiErr = parseInferenceOptionsRequest(c)
		c.Status(http.StatusOK)
	})

	req := httptest.NewRequest(http.MethodPost, "/x", bytes.NewReader(body))
	req.Header.Set("Content-Type", contentType)
	router.ServeHTTP(httptest.NewRecorder(), req)

	return opts, summary, apiErr
}

func parseJSON(t *testing.T, body string) (driver.InferenceOptions, labelSummary, *apiError) {
	t.Helper()
	return runParse(t, "application/json", []byte(body))
}

// buildMultipart 組出 multipart body（labelFileName 為空表示不帶檔案）。
func buildMultipart(t *testing.T, taskType, labelFileName, labelContent string) (string, []byte) {
	t.Helper()

	var buf bytes.Buffer
	w := multipart.NewWriter(&buf)
	if taskType != "" {
		if err := w.WriteField("taskType", taskType); err != nil {
			t.Fatalf("WriteField: %v", err)
		}
	}
	if labelFileName != "" {
		fw, err := w.CreateFormFile("labelFile", labelFileName)
		if err != nil {
			t.Fatalf("CreateFormFile: %v", err)
		}
		if _, err := fw.Write([]byte(labelContent)); err != nil {
			t.Fatalf("write file part: %v", err)
		}
	}
	if err := w.Close(); err != nil {
		t.Fatalf("close writer: %v", err)
	}
	return w.FormDataContentType(), buf.Bytes()
}

func requireNoAPIError(t *testing.T, err *apiError) {
	t.Helper()
	if err != nil {
		t.Fatalf("unexpected apiError: code=%s message=%s", err.code, err.message)
	}
}

func requireAPIError(t *testing.T, err *apiError, wantCode string) *apiError {
	t.Helper()
	if err == nil {
		t.Fatalf("expected apiError with code %s, got nil", wantCode)
	}
	if err.code != wantCode {
		t.Fatalf("error code = %q, want %q (message=%q)", err.code, wantCode, err.message)
	}
	return err
}

// ── JSON body ────────────────────────────────────────────────────────

func TestParseInferenceOptions_JSON_TaskTypeOnly(t *testing.T) {
	opts, _, err := parseJSON(t, `{"taskType":"classification"}`)
	requireNoAPIError(t, err)

	if opts.TaskType != "classification" {
		t.Errorf("TaskType = %q, want classification", opts.TaskType)
	}
	if opts.Labels != nil {
		t.Errorf("Labels = %v, want nil（沒帶 labels 就不該動 label 表）", opts.Labels)
	}
}

func TestParseInferenceOptions_JSON_LabelsOnly(t *testing.T) {
	opts, summary, err := parseJSON(t, `{"labels":["剪刀","石頭","布"]}`)
	requireNoAPIError(t, err)

	if opts.TaskType != "" {
		t.Errorf("TaskType = %q, want 空（沒帶就不該動解析方式）", opts.TaskType)
	}
	want := []string{"剪刀", "石頭", "布"}
	if !equalStringSlice(opts.Labels, want) {
		t.Errorf("Labels = %v, want %v", opts.Labels, want)
	}
	if summary.namedCount != 3 {
		t.Errorf("namedCount = %d, want 3", summary.namedCount)
	}
}

// 關鍵語意：空陣列 = 清空 label 表，必須與「沒帶欄位」區分。
func TestParseInferenceOptions_JSON_EmptyLabelsMeansClear(t *testing.T) {
	opts, summary, err := parseJSON(t, `{"labels":[]}`)
	requireNoAPIError(t, err)

	if opts.Labels == nil {
		t.Fatal("Labels = nil —— 空陣列被塌成 nil，「清空 label 表」的意圖丟失了")
	}
	if len(opts.Labels) != 0 {
		t.Errorf("len(Labels) = %d, want 0", len(opts.Labels))
	}
	if summary.namedCount != 0 {
		t.Errorf("namedCount = %d, want 0", summary.namedCount)
	}
}

// 對照組：沒帶 labels 欄位時 Labels 必須是 nil（= 不動）。
func TestParseInferenceOptions_JSON_AbsentLabelsMeansUnchanged(t *testing.T) {
	opts, _, err := parseJSON(t, `{"taskType":"classification"}`)
	requireNoAPIError(t, err)

	if opts.Labels != nil {
		t.Errorf("Labels = %v, want nil", opts.Labels)
	}
}

// JSON null 與「沒帶」同義 —— 都是不動。
func TestParseInferenceOptions_JSON_NullLabelsMeansUnchanged(t *testing.T) {
	opts, _, err := parseJSON(t, `{"taskType":"classification","labels":null}`)
	requireNoAPIError(t, err)

	if opts.Labels != nil {
		t.Errorf("Labels = %v, want nil", opts.Labels)
	}
}

func TestParseInferenceOptions_JSON_Both(t *testing.T) {
	opts, summary, err := parseJSON(t, `{"taskType":"classification","labels":["a","b"]}`)
	requireNoAPIError(t, err)

	if opts.TaskType != "classification" {
		t.Errorf("TaskType = %q", opts.TaskType)
	}
	if summary.namedCount != 2 {
		t.Errorf("namedCount = %d, want 2", summary.namedCount)
	}
}

func TestParseInferenceOptions_JSON_SparseLabelsCountedCorrectly(t *testing.T) {
	opts, summary, err := parseJSON(t, `{"labels":["a","","c"]}`)
	requireNoAPIError(t, err)

	if len(opts.Labels) != 3 {
		t.Errorf("len(Labels) = %d, want 3（稀疏佔位要保留，位置就是 class index）", len(opts.Labels))
	}
	if summary.namedCount != 2 {
		t.Errorf("namedCount = %d, want 2（空字串不算一筆）", summary.namedCount)
	}
}

func TestParseInferenceOptions_JSON_MalformedBody(t *testing.T) {
	_, _, err := parseJSON(t, `{not json`)
	requireAPIError(t, err, "BAD_REQUEST")
}

// ── 值域驗證（沿用燒錄時同一套）──────────────────────────────────────

func TestParseInferenceOptions_RejectsInvalidTaskType(t *testing.T) {
	// R-4：舊別名 detection 也要擋 —— bridge 收得下，但不讓兩套命名同時
	// 出現在 wire 上。與 POST /flash 的規則保持完全一致。
	bad := []string{
		"detection",
		"segmentation",
		"pose_estimation",
		"Classification",
		"classifcation",
		"garbage",
	}
	for _, tt := range bad {
		t.Run(tt, func(t *testing.T) {
			body := fmt.Sprintf(`{"taskType":%q}`, tt)
			_, _, err := parseJSON(t, body)
			e := requireAPIError(t, err, "VALIDATION_ERROR")
			if e.status != http.StatusBadRequest {
				t.Errorf("status = %d, want 400", e.status)
			}
			if !strings.Contains(e.message, "classification") ||
				!strings.Contains(e.message, "object_detection") {
				t.Errorf("message = %q, 應列出合法值", e.message)
			}
		})
	}
}

func TestParseInferenceOptions_AcceptsValidTaskType(t *testing.T) {
	for _, tt := range []string{"classification", "object_detection"} {
		t.Run(tt, func(t *testing.T) {
			opts, _, err := parseJSON(t, fmt.Sprintf(`{"taskType":%q}`, tt))
			requireNoAPIError(t, err)
			if opts.TaskType != tt {
				t.Errorf("TaskType = %q, want %q", opts.TaskType, tt)
			}
		})
	}
}

// 兩者都沒帶 = 呼叫端沒表達任何意圖。回 200 等於假裝做了事。
func TestParseInferenceOptions_RejectsEmptyRequest(t *testing.T) {
	cases := map[string]string{
		"空物件":          `{}`,
		"taskType 空字串": `{"taskType":""}`,
		"兩者皆 null":     `{"taskType":null,"labels":null}`,
	}
	for name, body := range cases {
		t.Run(name, func(t *testing.T) {
			_, _, err := parseJSON(t, body)
			requireAPIError(t, err, "BAD_REQUEST")
		})
	}
}

// 只帶空 labels 陣列是有意義的（清空），不該被「空請求」規則誤擋。
func TestParseInferenceOptions_EmptyLabelsAloneIsNotEmptyRequest(t *testing.T) {
	_, _, err := parseJSON(t, `{"labels":[]}`)
	requireNoAPIError(t, err)
}

// ── JSON labels 數量上限（S-2 / R-7）─────────────────────────────────

func TestParseInferenceOptions_JSON_RejectsTooManyLabels(t *testing.T) {
	labels := make([]string, labelfile.MaxIndex+2)
	for i := range labels {
		labels[i] = "x"
	}
	payload, err := json.Marshal(map[string]interface{}{"labels": labels})
	if err != nil {
		t.Fatalf("marshal: %v", err)
	}

	_, _, apiErr := runParse(t, "application/json", payload)
	requireAPIError(t, apiErr, "LABEL_TOO_LARGE")
}

func TestParseInferenceOptions_JSON_AcceptsExactlyMaxLabels(t *testing.T) {
	labels := make([]string, labelfile.MaxIndex+1)
	for i := range labels {
		labels[i] = "x"
	}
	payload, err := json.Marshal(map[string]interface{}{"labels": labels})
	if err != nil {
		t.Fatalf("marshal: %v", err)
	}

	_, _, apiErr := runParse(t, "application/json", payload)
	requireNoAPIError(t, apiErr)
}

// ── multipart 上傳 ───────────────────────────────────────────────────

func TestParseInferenceOptions_Multipart_LabelFile(t *testing.T) {
	ct, body := buildMultipart(t, "classification", "labels.txt", "0 剪刀\n1 石頭\n2 布\n")
	opts, summary, err := runParse(t, ct, body)
	requireNoAPIError(t, err)

	if opts.TaskType != "classification" {
		t.Errorf("TaskType = %q", opts.TaskType)
	}
	want := []string{"剪刀", "石頭", "布"}
	if !equalStringSlice(opts.Labels, want) {
		t.Errorf("Labels = %v, want %v", opts.Labels, want)
	}
	if summary.namedCount != 3 {
		t.Errorf("namedCount = %d, want 3", summary.namedCount)
	}
}

func TestParseInferenceOptions_Multipart_TaskTypeOnlyNoFile(t *testing.T) {
	ct, body := buildMultipart(t, "object_detection", "", "")
	opts, _, err := runParse(t, ct, body)
	requireNoAPIError(t, err)

	if opts.TaskType != "object_detection" {
		t.Errorf("TaskType = %q", opts.TaskType)
	}
	if opts.Labels != nil {
		t.Errorf("Labels = %v, want nil（沒上傳檔案就不該動 label 表）", opts.Labels)
	}
}

func TestParseInferenceOptions_Multipart_SparseLabelFile(t *testing.T) {
	ct, body := buildMultipart(t, "classification", "labels.txt", "0 a\n3 d\n")
	opts, summary, err := runParse(t, ct, body)
	requireNoAPIError(t, err)

	want := []string{"a", "", "", "d"}
	if !equalStringSlice(opts.Labels, want) {
		t.Errorf("Labels = %v, want %v", opts.Labels, want)
	}
	if summary.namedCount != 2 {
		t.Errorf("namedCount = %d, want 2", summary.namedCount)
	}
}

// 解析失敗要帶行號回去，前端才能指出是哪一行。
func TestParseInferenceOptions_Multipart_ParseErrorCarriesLine(t *testing.T) {
	ct, body := buildMultipart(t, "", "labels.txt", "0 a\n1 b\nabc c\n")
	_, _, err := runParse(t, ct, body)
	e := requireAPIError(t, err, "LABEL_PARSE_ERROR")

	if e.line != 3 {
		t.Errorf("line = %d, want 3", e.line)
	}
	if _, ok := e.body()["line"].(int); !ok {
		t.Error("回應 body 應包含 line 欄位")
	}
}

func TestParseInferenceOptions_Multipart_ParseErrorBodyOmitsLineWhenZero(t *testing.T) {
	ct, body := buildMultipart(t, "", "labels.txt", "\n\n\n")
	_, _, err := runParse(t, ct, body)
	e := requireAPIError(t, err, "LABEL_PARSE_ERROR")

	if _, present := e.body()["line"]; present {
		t.Error("與行號無關的錯誤不應帶 line 欄位（前端會亂標第 0 行）")
	}
}

func TestParseInferenceOptions_Multipart_RejectsOversizedFile(t *testing.T) {
	big := strings.Repeat("0 aaaaaaaa\n", labelfile.MaxFileSize/10+100)
	ct, body := buildMultipart(t, "", "labels.txt", big)
	_, _, err := runParse(t, ct, body)
	requireAPIError(t, err, "LABEL_TOO_LARGE")
}

func TestParseInferenceOptions_Multipart_RejectsBadExtension(t *testing.T) {
	ct, body := buildMultipart(t, "", "labels.exe", "0 a\n")
	_, _, err := runParse(t, ct, body)
	requireAPIError(t, err, "BAD_REQUEST")
}

func TestParseInferenceOptions_Multipart_AcceptsNamesExtension(t *testing.T) {
	ct, body := buildMultipart(t, "", "coco.names", "0 person\n")
	opts, _, err := runParse(t, ct, body)
	requireNoAPIError(t, err)

	if !equalStringSlice(opts.Labels, []string{"person"}) {
		t.Errorf("Labels = %v", opts.Labels)
	}
}

func TestParseInferenceOptions_Multipart_RejectsInvalidTaskType(t *testing.T) {
	ct, body := buildMultipart(t, "detection", "labels.txt", "0 a\n")
	_, _, err := runParse(t, ct, body)
	requireAPIError(t, err, "VALIDATION_ERROR")
}

func TestParseInferenceOptions_Multipart_RejectsEmptyRequest(t *testing.T) {
	ct, body := buildMultipart(t, "", "", "")
	_, _, err := runParse(t, ct, body)
	requireAPIError(t, err, "BAD_REQUEST")
}

// 上傳的 index 超過上限 → 由 labelfile 擋下並回 LABEL_PARSE_ERROR。
// 若這道防線失效，handler 會嘗試配置巨大 slice。
func TestParseInferenceOptions_Multipart_RejectsHugeIndex(t *testing.T) {
	ct, body := buildMultipart(t, "", "labels.txt", "999999999 boom\n")
	_, _, err := runParse(t, ct, body)
	requireAPIError(t, err, "LABEL_PARSE_ERROR")
}

// ── handler 分支（不需要 device session 的部分）──────────────────────

// postOptions 呼叫 SetInferenceOptions 並回傳 status / 解析後 body。
func postOptions(t *testing.T, h *DeviceHandler, contentType string, body []byte) (int, map[string]interface{}) {
	t.Helper()

	router := gin.New()
	router.POST("/devices/:id/inference/options", h.SetInferenceOptions)

	req := httptest.NewRequest(http.MethodPost, "/devices/dev-1/inference/options", bytes.NewReader(body))
	req.Header.Set("Content-Type", contentType)
	w := httptest.NewRecorder()
	router.ServeHTTP(w, req)

	parsed := map[string]interface{}{}
	_ = json.Unmarshal(w.Body.Bytes(), &parsed)
	return w.Code, parsed
}

func TestSetInferenceOptions_DeviceNotFound(t *testing.T) {
	h := &DeviceHandler{deviceMgr: device.NewManager(device.NewRegistry(), "")}

	status, parsed := postOptions(t, h, "application/json", []byte(`{"taskType":"classification"}`))

	if status != http.StatusNotFound {
		t.Errorf("status = %d, want 404", status)
	}
	if got := errorCode(parsed); got != "DEVICE_NOT_FOUND" {
		t.Errorf("error.code = %q, want DEVICE_NOT_FOUND", got)
	}
}

// device 查找必須排在 body 解析之前 —— 對不存在的裝置回「body 有問題」
// 會把使用者引去改 payload，而真正的問題是裝置不在。
func TestSetInferenceOptions_DeviceLookupPrecedesBodyValidation(t *testing.T) {
	h := &DeviceHandler{deviceMgr: device.NewManager(device.NewRegistry(), "")}

	status, parsed := postOptions(t, h, "application/json", []byte(`{not json`))

	if status != http.StatusNotFound {
		t.Errorf("status = %d, want 404（裝置查找應先於 body 解析）", status)
	}
	if got := errorCode(parsed); got != "DEVICE_NOT_FOUND" {
		t.Errorf("error.code = %q, want DEVICE_NOT_FOUND", got)
	}
}

// ── 介面契約 ─────────────────────────────────────────────────────────

// *kneron.KneronDriver 必須真的滿足 InferenceOptionsDriver。
//
// 這是整條鏈路唯一會「靜默壞掉」的接點：handler 用 type assert 取得能力，
// 若 driver 的 method 簽章改了（或被誤刪），編譯完全不會報錯 —— endpoint
// 會對所有裝置回 UNSUPPORTED_DEVICE，而且只有實機才看得出來。
//
// 刻意 assert 具體型別而非自己寫一個滿足介面的 stub：stub 只證明「我寫的
// stub 符合我寫的介面」，對真正的實作零保障。
var _ InferenceOptionsDriver = (*kneron.KneronDriver)(nil)

// KneronDriver 同時必須仍是合法的 driver.DeviceDriver —— 加新能力不能
// 破壞既有契約。
var _ driver.DeviceDriver = (*kneron.KneronDriver)(nil)

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

func equalStringSlice(a, b []string) bool {
	if len(a) != len(b) {
		return false
	}
	for i := range a {
		if a[i] != b[i] {
			return false
		}
	}
	return true
}