package controllers

import (
	"encoding/json"
	"fmt"
	"net/http"
	"net/http/httptest"
	"os"
	"path/filepath"
	"testing"
	"time"

	"apiserver/backend"
	"apiserver/common"
	"apiserver/models"
	"apiserver/store"
	"apiserver/utils"

	"github.com/gin-gonic/gin"
	"go.uber.org/zap"
)

// mockFetchFile simulates FetchFile by reading from the local filesystem.
// It is installed by resetJobsState() so all output endpoint tests use it.
func mockFetchFile(jobid uint64, filepath string, offset uint64, maxBytes uint32) (*backend.FetchFileResult, error) {
	data, err := os.ReadFile(filepath)
	if err != nil {
		return nil, err
	}
	fileSize := uint64(len(data))
	if offset >= fileSize {
		return &backend.FetchFileResult{FileSize: fileSize, BytesRead: 0}, nil
	}
	chunk := data[offset:]
	if maxBytes > 0 && uint32(len(chunk)) > maxBytes {
		chunk = chunk[:maxBytes]
	}
	return &backend.FetchFileResult{
		Content:   chunk,
		FileSize:  fileSize,
		BytesRead: uint32(len(chunk)),
	}, nil
}

func resetJobsState() {
	store.InitStores()
	utils.Log = zap.NewNop()
	initTestAuthConfig() // ensure JWT parsing works in all output tests
	fetchFile = mockFetchFile
}

func setupTestJob(t *testing.T, tmpDir string) {
	t.Helper()

	// OutFile/ErrFile use %J placeholder; resolveOutputPath replaces %J with
	// the formatted job ID (FormatJobID(1001) = "0-0-0-1001" for small test IDs).
	outFile := filepath.Join(tmpDir, "job_%J.out")
	errFile := filepath.Join(tmpDir, "job_%J.err")

	job := models.JobInfo{
		Unique_JobID: 1001,
		JobID:        1001,
		ArrayIdx:     0,
		SubmitUser:   "testuser",
		JobStatus:    0x02, // RUN
		OutFile:      outFile,
		ErrFile:      errFile,
		CWD:          tmpDir,
	}
	store.Jobs.Put(1001, job)

	// Write to the resolved paths (with %J replaced by formatted ID "0-0-0-1001").
	os.WriteFile(filepath.Join(tmpDir, "job_0-0-0-1001.out"), []byte("line1\nline2\nline3\nline4\nline5\n"), 0644)
	os.WriteFile(filepath.Join(tmpDir, "job_0-0-0-1001.err"), []byte("err1\nerr2\n"), 0644)
}

func setupTestRouter() *gin.Engine {
	gin.SetMode(gin.TestMode)
	r := gin.New()
	handler := &JobController{}
	r.GET("/xce/v1/jobs/:jobids/output", handler.GetJobOutput)
	return r
}

// testToken returns a signed JWT for "testuser" valid for 1 hour.
// initTestAuthConfig() must be called before using this token.
func testToken() string {
	return "Bearer " + signTestJWT("testuser", "admin", time.Now().Add(time.Hour))
}

func decodeResponse(t *testing.T, w *httptest.ResponseRecorder, v interface{}) {
	t.Helper()
	t.Logf("response body: %s", w.Body.String())
	if err := json.Unmarshal(w.Body.Bytes(), v); err != nil {
		t.Fatalf("decode response: %v", err)
	}
}

func TestGetJobOutput_TailLines(t *testing.T) {
	resetJobsState()

	tmpDir := t.TempDir()
	setupTestJob(t, tmpDir)

	router := setupTestRouter()

	w := httptest.NewRecorder()
	req, _ := http.NewRequest("GET", "/xce/v1/jobs/1001/output?lines=2", nil)
	req.Header.Set("Authorization", testToken())
	router.ServeHTTP(w, req)

	if w.Code != http.StatusOK {
		t.Fatalf("expected 200, got %d: %s", w.Code, w.Body.String())
	}

	var resp struct {
		Code int        `json:"code"`
		Data OutputData `json:"data"`
	}
	decodeResponse(t, w, &resp)

	if resp.Data.Content != "line4\nline5\n" {
		t.Errorf("content = %q, want %q", resp.Data.Content, "line4\nline5\n")
	}
	if resp.Data.Offset != 30 {
		t.Errorf("offset = %d, want 30", resp.Data.Offset)
	}
	if resp.Data.Done {
		t.Error("done should be false for running job")
	}
	if resp.Data.JobStatus != "RUN" {
		t.Errorf("job_status = %q, want RUN", resp.Data.JobStatus)
	}
}

func TestGetJobOutput_FromOffset(t *testing.T) {
	resetJobsState()

	tmpDir := t.TempDir()
	setupTestJob(t, tmpDir)

	router := setupTestRouter()

	w := httptest.NewRecorder()
	req, _ := http.NewRequest("GET", "/xce/v1/jobs/1001/output?offset=12", nil)
	req.Header.Set("Authorization", testToken())
	router.ServeHTTP(w, req)

	if w.Code != http.StatusOK {
		t.Fatalf("expected 200, got %d: %s", w.Code, w.Body.String())
	}

	var resp struct {
		Code int        `json:"code"`
		Data OutputData `json:"data"`
	}
	decodeResponse(t, w, &resp)

	if resp.Data.Content != "line3\nline4\nline5\n" {
		t.Errorf("content = %q, want %q", resp.Data.Content, "line3\nline4\nline5\n")
	}
	if resp.Data.Offset != 30 {
		t.Errorf("offset = %d, want 30", resp.Data.Offset)
	}
}

func TestGetJobOutput_FileNotFound(t *testing.T) {
	resetJobsState()

	tmpDir := t.TempDir()
	outFile := filepath.Join(tmpDir, "job_%J.out")

	job := models.JobInfo{
		Unique_JobID: 2001,
		JobID:        2001,
		ArrayIdx:     0,
		SubmitUser:   "testuser",
		JobStatus:    0x02,
		OutFile:      outFile,
	}
	store.Jobs.Put(2001, job)

	router := setupTestRouter()

	w := httptest.NewRecorder()
	req, _ := http.NewRequest("GET", "/xce/v1/jobs/2001/output?lines=10", nil)
	req.Header.Set("Authorization", testToken())
	router.ServeHTTP(w, req)

	var resp struct {
		Code int `json:"code"`
	}
	decodeResponse(t, w, &resp)

	if resp.Code != common.ERROR_READ_FILE_CODE {
		t.Errorf("code = %d, want %d", resp.Code, common.ERROR_READ_FILE_CODE)
	}
}

func TestGetJobOutput_NoOutputFileConfigured(t *testing.T) {
	resetJobsState()

	job := models.JobInfo{
		Unique_JobID: 3001,
		JobID:        3001,
		ArrayIdx:     0,
		SubmitUser:   "testuser",
		JobStatus:    0x02,
		OutFile:      "",
	}
	store.Jobs.Put(3001, job)

	router := setupTestRouter()

	w := httptest.NewRecorder()
	req, _ := http.NewRequest("GET", "/xce/v1/jobs/3001/output?lines=10", nil)
	req.Header.Set("Authorization", testToken())
	router.ServeHTTP(w, req)

	// resolveOutputPath uses the worker default (/tmp/job_0-0-0-3001_task0.out).
	// That file does not exist, so we expect a read error (501).
	var resp struct {
		Code int `json:"code"`
	}
	decodeResponse(t, w, &resp)

	if resp.Code != common.ERROR_READ_FILE_CODE {
		t.Errorf("code = %d, want %d", resp.Code, common.ERROR_READ_FILE_CODE)
	}
}

// TestGetJobOutput_DefaultPathFallback verifies that when OutFile is empty,
// the worker's default output path is used and content is returned successfully.
func TestGetJobOutput_DefaultPathFallback(t *testing.T) {
	resetJobsState()

	// Use a real-ish packed job ID: cluster=1, apiserver=0, ts=1778311965, seq=0
	// FormatJobID → "1-0-1778311965-0"
	// WorkerDefaultOutputPath → "/tmp/job_1-0-1778311965-0_task0.out"
	const uniqueID = int64(0x0100000006A04BDD << 0) // MakeJobID(1,0,1778311965,0,0)
	// Use backend.MakeJobID directly for clarity; compute inline:
	// clusterID=1 at bit 56, timestamp=1778311965 at bit 20
	// packed = (1 << 56) | (1778311965 << 20)
	const packedID = int64((uint64(1) << 56) | (uint64(1778311965) << 20))

	// Install a fetchFile that reads from a tmpdir-based path instead of /tmp
	// to avoid touching /tmp during tests.
	tmpDir := t.TempDir()
	workerDefault := backend.WorkerDefaultOutputPath(packedID, 0) // /tmp/job_1-0-1778311965-0_task0.out
	formattedID := backend.FormatJobID(packedID)                  // "1-0-1778311965-0"
	localFile := filepath.Join(tmpDir, "job_"+formattedID+"_task0.out")
	os.WriteFile(localFile, []byte("worker output line\n"), 0644)

	// Override fetchFile for this test to redirect /tmp paths to tmpDir.
	origFetchFile := fetchFile
	fetchFile = func(jobid uint64, path string, offset uint64, maxBytes uint32) (*backend.FetchFileResult, error) {
		if path == workerDefault {
			path = localFile
		}
		return mockFetchFile(jobid, path, offset, maxBytes)
	}
	defer func() { fetchFile = origFetchFile }()

	job := models.JobInfo{
		Unique_JobID: packedID,
		JobID:        packedID,
		ArrayIdx:     0,
		SubmitUser:   "testuser",
		JobStatus:    0x02, // RUN
		OutFile:      "",   // no OutFile — should fall back to worker default
	}
	store.Jobs.Put(uint64(packedID), job)

	router := setupTestRouter()

	w := httptest.NewRecorder()
	jobIDStr := fmt.Sprintf("%d", packedID)
	req, _ := http.NewRequest("GET", "/xce/v1/jobs/"+jobIDStr+"/output?lines=10", nil)
	req.Header.Set("Authorization", testToken())
	router.ServeHTTP(w, req)

	if w.Code != http.StatusOK {
		t.Fatalf("expected 200, got %d: %s", w.Code, w.Body.String())
	}

	var resp struct {
		Data OutputData `json:"data"`
	}
	decodeResponse(t, w, &resp)

	if resp.Data.Content != "worker output line\n" {
		t.Errorf("content = %q, want %q", resp.Data.Content, "worker output line\n")
	}
}

func TestGetJobOutput_PlaceholderResolution(t *testing.T) {
	resetJobsState()

	tmpDir := t.TempDir()
	// FormatJobID(4001) = "0-0-0-4001" for small test IDs
	outFile := filepath.Join(tmpDir, "job_0-0-0-4001.out")

	job := models.JobInfo{
		Unique_JobID: 4001,
		JobID:        4001,
		ArrayIdx:     0,
		SubmitUser:   "testuser",
		JobStatus:    0x02,
		OutFile:      filepath.Join(tmpDir, "job_%J.out"),
	}
	store.Jobs.Put(4001, job)

	os.WriteFile(outFile, []byte("placeholder resolved\n"), 0644)

	router := setupTestRouter()

	w := httptest.NewRecorder()
	req, _ := http.NewRequest("GET", "/xce/v1/jobs/4001/output?lines=10", nil)
	req.Header.Set("Authorization", testToken())
	router.ServeHTTP(w, req)

	if w.Code != http.StatusOK {
		t.Fatalf("expected 200, got %d: %s", w.Code, w.Body.String())
	}

	var resp struct {
		Data OutputData `json:"data"`
	}
	decodeResponse(t, w, &resp)

	if resp.Data.Content != "placeholder resolved\n" {
		t.Errorf("content = %q, want %q", resp.Data.Content, "placeholder resolved\n")
	}
}

func TestGetJobOutput_JobNotFound(t *testing.T) {
	resetJobsState()

	router := setupTestRouter()

	w := httptest.NewRecorder()
	req, _ := http.NewRequest("GET", "/xce/v1/jobs/99999/output?lines=10", nil)
	req.Header.Set("Authorization", testToken())
	router.ServeHTTP(w, req)

	if w.Code != http.StatusNotFound {
		t.Errorf("expected 404, got %d: %s", w.Code, w.Body.String())
	}
}

func TestGetJobOutput_InvalidParams(t *testing.T) {
	resetJobsState()

	router := setupTestRouter()

	tests := []struct {
		name       string
		url        string
		expectCode int
	}{
		{"invalid offset", "/xce/v1/jobs/1001/output?offset=abc", http.StatusBadRequest},
		{"invalid lines zero", "/xce/v1/jobs/1001/output?lines=0", http.StatusBadRequest},
		{"invalid type", "/xce/v1/jobs/1001/output?type=combined", http.StatusBadRequest},
	}

	for _, tc := range tests {
		t.Run(tc.name, func(t *testing.T) {
			w := httptest.NewRecorder()
			req, _ := http.NewRequest("GET", tc.url, nil)
			req.Header.Set("Authorization", testToken())
			router.ServeHTTP(w, req)
			if w.Code != tc.expectCode {
				t.Errorf("expected %d, got %d: %s", tc.expectCode, w.Code, w.Body.String())
			}
		})
	}
}

func TestLastNLines(t *testing.T) {
	tests := []struct {
		name   string
		input  []byte
		n      int
		expect string
	}{
		{"tail 2 of 5", []byte("a\nb\nc\nd\ne\n"), 2, "d\ne\n"},
		{"tail all", []byte("a\nb\n"), 100, "a\nb\n"},
		{"empty", []byte(""), 10, ""},
		{"no trailing newline", []byte("no newline"), 5, "no newline"},
	}

	for _, tc := range tests {
		t.Run(tc.name, func(t *testing.T) {
			got := lastNLines(tc.input, tc.n)
			if got != tc.expect {
				t.Errorf("lastNLines(%q, %d) = %q, want %q", tc.input, tc.n, got, tc.expect)
			}
		})
	}
}

func TestResolveOutputPath(t *testing.T) {
	// FormatJobID(123) = "0-0-0-123" for small packed IDs (cluster=0, apiserver=0, ts=0, seq=123)
	job := models.JobInfo{
		Unique_JobID: 123,
		JobID:        123,
		ArrayIdx:     2,
		SubmitUser:   "alice",
		CWD:          "/home/alice/work",
	}

	tests := []struct {
		input    string
		expected string
	}{
		{"/tmp/job_%J.out", "/tmp/job_0-0-0-123.out"},
		{"/tmp/job_%J_%I.out", "/tmp/job_0-0-0-123_2.out"},
		{"/tmp/job_%U.out", "/tmp/job_alice.out"},
		{"/tmp/job_%C.out", "/tmp/job_/home/alice/work.out"},
		// empty path → worker default for task 0
		{"", "/tmp/job_0-0-0-123_task0.out"},
		{"/tmp/fixed.out", "/tmp/fixed.out"},
	}

	for _, tc := range tests {
		t.Run(tc.input, func(t *testing.T) {
			result := resolveOutputPath(tc.input, job)
			if result != tc.expected {
				t.Errorf("resolveOutputPath(%q) = %q, want %q", tc.input, result, tc.expected)
			}
		})
	}
}

func TestGetJobOutput_Stderr(t *testing.T) {
	resetJobsState()

	tmpDir := t.TempDir()
	errFile := filepath.Join(tmpDir, "job_5001.err")

	job := models.JobInfo{
		Unique_JobID: 5001,
		JobID:        5001,
		ArrayIdx:     0,
		SubmitUser:   "testuser",
		JobStatus:    0x02,
		ErrFile:      errFile,
	}
	store.Jobs.Put(5001, job)

	os.WriteFile(errFile, []byte("stderr output\n"), 0644)

	router := setupTestRouter()

	w := httptest.NewRecorder()
	req, _ := http.NewRequest("GET", "/xce/v1/jobs/5001/output?type=stderr&lines=10", nil)
	req.Header.Set("Authorization", testToken())
	router.ServeHTTP(w, req)

	if w.Code != http.StatusOK {
		t.Fatalf("expected 200, got %d: %s", w.Code, w.Body.String())
	}

	var resp struct {
		Data OutputData `json:"data"`
	}
	decodeResponse(t, w, &resp)

	if resp.Data.Content != "stderr output\n" {
		t.Errorf("content = %q, want %q", resp.Data.Content, "stderr output\n")
	}
}

func TestGetJobOutput_DoneJob(t *testing.T) {
	resetJobsState()

	tmpDir := t.TempDir()
	outFile := filepath.Join(tmpDir, "job_6001.out")

	job := models.JobInfo{
		Unique_JobID: 6001,
		JobID:        6001,
		ArrayIdx:     0,
		SubmitUser:   "testuser",
		JobStatus:    0x08, // DONE
		OutFile:      outFile,
	}
	store.Jobs.Put(6001, job)

	os.WriteFile(outFile, []byte("finished output\n"), 0644)

	router := setupTestRouter()

	w := httptest.NewRecorder()
	req, _ := http.NewRequest("GET", "/xce/v1/jobs/6001/output?lines=10", nil)
	req.Header.Set("Authorization", testToken())
	router.ServeHTTP(w, req)

	if w.Code != http.StatusOK {
		t.Fatalf("expected 200, got %d: %s", w.Code, w.Body.String())
	}

	var resp struct {
		Data OutputData `json:"data"`
	}
	decodeResponse(t, w, &resp)

	if !resp.Data.Done {
		t.Error("done should be true for finished job")
	}
	if resp.Data.JobStatus != "DONE" {
		t.Errorf("job_status = %q, want DONE", resp.Data.JobStatus)
	}
}