package delegation

import (
	"context"
	"encoding/json"
	"errors"
	"io"
	"log"
	"os"
	"path/filepath"
	"sync"
	"testing"
	"time"

	"forge.secuaas.ovh/olivier/claude-failover/internal/router"
	"forge.secuaas.ovh/olivier/claude-failover/internal/secutools"
)

// fakeClient is an in-memory secutools.Client implementation for tests.
// It supports preloaded responses keyed by job_id and a counter of calls.
type fakeClient struct {
	mu        sync.Mutex
	nextJobID int
	statuses  map[string]string                 // job_id → current status
	results   map[string]*secutools.JobResult   // job_id → result
	statusErr error
	submitErr error
}

func newFakeClient() *fakeClient {
	return &fakeClient{
		statuses: make(map[string]string),
		results:  make(map[string]*secutools.JobResult),
	}
}

func (f *fakeClient) SubmitJob(_ context.Context, req *secutools.JobRequest) (*secutools.JobResponse, error) {
	f.mu.Lock()
	defer f.mu.Unlock()
	if f.submitErr != nil {
		return nil, f.submitErr
	}
	f.nextJobID++
	id := "job-" + itoa(f.nextJobID)
	f.statuses[id] = "pending"
	return &secutools.JobResponse{JobID: id, Status: "pending"}, nil
}

func (f *fakeClient) GetJob(_ context.Context, id string) (*secutools.JobStatus, error) {
	f.mu.Lock()
	defer f.mu.Unlock()
	if f.statusErr != nil {
		return nil, f.statusErr
	}
	st, ok := f.statuses[id]
	if !ok {
		return nil, errors.New("unknown job: " + id)
	}
	out := &secutools.JobStatus{JobID: id, Status: st}
	if r, ok := f.results[id]; ok {
		out.Provider = r.Provider
	}
	return out, nil
}

func (f *fakeClient) WaitForResult(_ context.Context, id string, _ time.Duration) (*secutools.JobResult, error) {
	f.mu.Lock()
	defer f.mu.Unlock()
	if r, ok := f.results[id]; ok {
		return r, nil
	}
	return nil, errors.New("no result for " + id)
}

// setStatus is a test helper to drive job lifecycles.
func (f *fakeClient) setStatus(id, status string) {
	f.mu.Lock()
	defer f.mu.Unlock()
	f.statuses[id] = status
}

func (f *fakeClient) setResult(id string, r *secutools.JobResult) {
	f.mu.Lock()
	defer f.mu.Unlock()
	f.results[id] = r
}

// itoa is a tiny stdlib-free int-to-string for fake job IDs.
func itoa(n int) string {
	if n == 0 {
		return "0"
	}
	var b []byte
	for n > 0 {
		b = append([]byte{byte('0' + n%10)}, b...)
		n /= 10
	}
	return string(b)
}

// quietLogger discards log output.
func quietLogger() *log.Logger {
	return log.New(io.Discard, "", 0)
}

func setupProject(t *testing.T) (projectDir, taskPath string) {
	t.Helper()
	projectDir = t.TempDir()
	inbox := filepath.Join(projectDir, ".agent-queue", "inbox")
	if err := os.MkdirAll(inbox, 0755); err != nil {
		t.Fatal(err)
	}
	taskPath = filepath.Join(inbox, "task-001.md")
	if err := os.WriteFile(taskPath, []byte("---\ntitle: Test\n---\nDo a thing."), 0644); err != nil {
		t.Fatal(err)
	}
	return projectDir, taskPath
}

func TestSubmit_WritesMarkerAndIncrementsCounter(t *testing.T) {
	fc := newFakeClient()
	mgr := New(fc, 100*time.Millisecond)
	mgr.SetLogger(quietLogger())

	projectDir, taskPath := setupProject(t)

	job, err := mgr.Submit(context.Background(), projectDir, taskPath, "Do a thing.",
		router.ProviderGPU, secutools.PriorityHigh)
	if err != nil {
		t.Fatalf("Submit: %v", err)
	}
	if job.JobID == "" {
		t.Fatal("expected non-empty job id")
	}
	if mgr.Counters.Active.Load() != 1 {
		t.Errorf("expected Active=1, got %d", mgr.Counters.Active.Load())
	}

	// Marker file must exist and decode back to the same job_id.
	markerPath := taskPath + ".delegated"
	data, err := os.ReadFile(markerPath)
	if err != nil {
		t.Fatalf("missing marker: %v", err)
	}
	var mk Marker
	if err := json.Unmarshal(data, &mk); err != nil {
		t.Fatalf("decode marker: %v", err)
	}
	if mk.JobID != job.JobID || mk.Provider != "gpu" {
		t.Errorf("marker mismatch: %+v", mk)
	}
}

func TestSubmit_RejectsNonDelegatedProvider(t *testing.T) {
	mgr := New(newFakeClient(), time.Millisecond)
	mgr.SetLogger(quietLogger())
	_, taskPath := setupProject(t)

	_, err := mgr.Submit(context.Background(), filepath.Dir(filepath.Dir(filepath.Dir(taskPath))),
		taskPath, "p", router.ProviderClaudeCode, secutools.PriorityDefault)
	if err == nil {
		t.Fatal("expected error when provider is claude-code (non-delegated)")
	}
}

func TestReap_CompletesJobAndMovesToDone(t *testing.T) {
	fc := newFakeClient()
	mgr := New(fc, time.Millisecond)
	mgr.SetLogger(quietLogger())

	projectDir, taskPath := setupProject(t)

	job, err := mgr.Submit(context.Background(), projectDir, taskPath, "p",
		router.ProviderAuto, secutools.PriorityDefault)
	if err != nil {
		t.Fatal(err)
	}

	// Drive the fake into completed state.
	fc.setStatus(job.JobID, "completed")
	fc.setResult(job.JobID, &secutools.JobResult{
		JobID: job.JobID, Response: "Hello world", Provider: "gpu",
		Model: "qwen-coder", CostCAD: 0.012,
	})

	mgr.reapOnce(context.Background())

	if mgr.Counters.Active.Load() != 0 {
		t.Errorf("expected Active=0 after completion, got %d", mgr.Counters.Active.Load())
	}
	if mgr.Counters.CompletedTotal.Load() != 1 {
		t.Errorf("expected CompletedTotal=1, got %d", mgr.Counters.CompletedTotal.Load())
	}

	// done/ contains the result.
	donePath := filepath.Join(projectDir, ".agent-queue", "done", "task-001.md")
	doneBody, err := os.ReadFile(donePath)
	if err != nil {
		t.Fatalf("missing done/ file: %v", err)
	}
	if !contains(string(doneBody), "Hello world") || !contains(string(doneBody), "provider: gpu") {
		t.Errorf("done body missing expected fields:\n%s", doneBody)
	}

	// Inbox marker and original .md are gone.
	if _, err := os.Stat(taskPath + ".delegated"); !os.IsNotExist(err) {
		t.Error("marker should be removed after completion")
	}
	if _, err := os.Stat(taskPath); !os.IsNotExist(err) {
		t.Error("inbox .md should be removed after completion")
	}
}

func TestReap_FailedJobMovesToFailed(t *testing.T) {
	fc := newFakeClient()
	mgr := New(fc, time.Millisecond)
	mgr.SetLogger(quietLogger())

	projectDir, taskPath := setupProject(t)

	job, err := mgr.Submit(context.Background(), projectDir, taskPath, "p",
		router.ProviderGemini, secutools.PriorityLow)
	if err != nil {
		t.Fatal(err)
	}

	fc.setStatus(job.JobID, "failed")
	mgr.reapOnce(context.Background())

	if mgr.Counters.FailedTotal.Load() != 1 {
		t.Errorf("expected FailedTotal=1, got %d", mgr.Counters.FailedTotal.Load())
	}
	failedPath := filepath.Join(projectDir, ".agent-queue", "failed", "task-001.md")
	if _, err := os.Stat(failedPath); err != nil {
		t.Errorf("failed/ file missing: %v", err)
	}
}

func TestLoadFromDisk_RestoresMarkers(t *testing.T) {
	fc := newFakeClient()
	mgr := New(fc, time.Millisecond)
	mgr.SetLogger(quietLogger())

	projectDir, taskPath := setupProject(t)

	// Pre-write a marker on disk simulating a daemon restart.
	mk := Marker{
		Project: projectDir, TaskFile: taskPath, JobID: "preexisting-job",
		Provider: "gpu", StartedAt: time.Now().UTC().Add(-1 * time.Minute),
	}
	if err := writeMarker(taskPath+".delegated", mk); err != nil {
		t.Fatal(err)
	}

	if err := mgr.LoadFromDisk([]string{projectDir}); err != nil {
		t.Fatal(err)
	}
	if mgr.Counters.Active.Load() != 1 {
		t.Errorf("expected Active=1 after LoadFromDisk, got %d", mgr.Counters.Active.Load())
	}
	active := mgr.Active()
	if len(active) != 1 || active[0].JobID != "preexisting-job" {
		t.Errorf("Active() mismatch: %+v", active)
	}
}

func TestActive_ReturnsCurrentJobs(t *testing.T) {
	fc := newFakeClient()
	mgr := New(fc, time.Millisecond)
	mgr.SetLogger(quietLogger())

	projectDir, taskPath := setupProject(t)
	if _, err := mgr.Submit(context.Background(), projectDir, taskPath, "p",
		router.ProviderGPU, secutools.PriorityDefault); err != nil {
		t.Fatal(err)
	}

	got := mgr.Active()
	if len(got) != 1 {
		t.Fatalf("expected 1 active job, got %d", len(got))
	}
	if got[0].Provider != "gpu" || got[0].Project != projectDir {
		t.Errorf("active[0] mismatch: %+v", got[0])
	}
}

// TestEndToEnd_InboxToDone exercises the full happy path:
// inbox → Submit → reapOnce (status=completed) → done/.
func TestEndToEnd_InboxToDone(t *testing.T) {
	fc := newFakeClient()
	mgr := New(fc, time.Millisecond)
	mgr.SetLogger(quietLogger())

	projectDir, taskPath := setupProject(t)

	job, err := mgr.Submit(context.Background(), projectDir, taskPath,
		"Summarize this", router.ProviderAuto, secutools.PriorityDefault)
	if err != nil {
		t.Fatal(err)
	}

	// Simulate the secutools backend completing the job.
	fc.setStatus(job.JobID, "completed")
	fc.setResult(job.JobID, &secutools.JobResult{
		JobID: job.JobID, Response: "Summary text",
		Provider: "claude-haiku", Model: "haiku-3-5", CostCAD: 0.0005,
	})

	mgr.reapOnce(context.Background())

	donePath := filepath.Join(projectDir, ".agent-queue", "done", "task-001.md")
	body, err := os.ReadFile(donePath)
	if err != nil {
		t.Fatalf("missing done/ file: %v", err)
	}
	want := []string{"Summary text", "provider: claude-haiku", "cost_cad: 0.0005"}
	for _, w := range want {
		if !contains(string(body), w) {
			t.Errorf("done body missing %q:\n%s", w, body)
		}
	}
}

func contains(s, sub string) bool {
	return len(s) >= len(sub) && (sub == "" || indexOf(s, sub) >= 0)
}

func indexOf(s, sub string) int {
	for i := 0; i+len(sub) <= len(s); i++ {
		if s[i:i+len(sub)] == sub {
			return i
		}
	}
	return -1
}