package garmin

import (
	"bufio"
	"bytes"
	"context"
	"encoding/json"
	"errors"
	"io"
	"log/slog"
	"os/exec"
	"strings"
	"testing"
	"time"

	"geniusrun/backend/internal/log"
)

// wireResponsePayload is what a fake wrapper handler returns for one
// request; the harness fills in the response ID.
type wireResponsePayload struct {
	result   json.RawMessage
	err      string
	notFound bool
}

func fakeResult(v any) wireResponsePayload {
	b, err := json.Marshal(v)
	if err != nil {
		panic(err)
	}
	return wireResponsePayload{result: b}
}

func fakeError(msg string) wireResponsePayload {
	return wireResponsePayload{err: msg}
}

func fakeNotFoundError(msg string) wireResponsePayload {
	return wireResponsePayload{err: msg, notFound: true}
}

// newFakeWrapperClient wires a subprocessClient to an in-process goroutine
// that plays the Python wrapper's role, so protocol-level Go logic can be
// tested without python3/garminconnect installed.
func newFakeWrapperClient(t *testing.T, handle func(cmd string, params json.RawMessage) wireResponsePayload) *subprocessClient {
	t.Helper()

	reqR, reqW := io.Pipe()
	respR, respW := io.Pipe()
	t.Cleanup(func() {
		reqW.Close()
		respW.Close()
	})

	go func() {
		scanner := bufio.NewScanner(reqR)
		scanner.Buffer(make([]byte, 0, 64*1024), maxWrapperLineBytes)
		enc := json.NewEncoder(respW)
		for scanner.Scan() {
			var req struct {
				ID     int             `json:"id"`
				Cmd    string          `json:"cmd"`
				Params json.RawMessage `json:"params"`
			}
			if err := json.Unmarshal(scanner.Bytes(), &req); err != nil {
				continue
			}
			payload := handle(req.Cmd, req.Params)
			resp := wireResponse{ID: req.ID, Result: payload.result, Error: payload.err, NotFound: payload.notFound}
			if err := enc.Encode(resp); err != nil {
				return
			}
		}
	}()

	scanner := bufio.NewScanner(respR)
	scanner.Buffer(make([]byte, 0, 64*1024), maxWrapperLineBytes)

	return &subprocessClient{
		started: true,
		enc:     json.NewEncoder(reqW),
		scanner: scanner,
	}
}

func TestSubprocessClient_RoundTrip_DetectsIDMismatch(t *testing.T) {
	reqR, reqW := io.Pipe()
	respR, respW := io.Pipe()
	defer reqW.Close()
	defer respW.Close()

	go func() {
		scanner := bufio.NewScanner(reqR)
		scanner.Buffer(make([]byte, 0, 64*1024), maxWrapperLineBytes)
		scanner.Scan() // read and discard the one request
		json.NewEncoder(respW).Encode(wireResponse{ID: 999, Result: json.RawMessage(`{}`)})
	}()

	scanner := bufio.NewScanner(respR)
	scanner.Buffer(make([]byte, 0, 64*1024), maxWrapperLineBytes)
	c := &subprocessClient{started: true, enc: json.NewEncoder(reqW), scanner: scanner}

	_, err := c.roundTrip(context.Background(), "authenticate", nil)
	if err == nil || !strings.Contains(err.Error(), "id mismatch") {
		t.Fatalf("roundTrip error = %v, want an id mismatch error", err)
	}
}

func TestSubprocessClient_RoundTrip_SubprocessClosedIsError(t *testing.T) {
	reqR, reqW := io.Pipe()
	respR, respW := io.Pipe()
	defer reqW.Close()

	go func() {
		scanner := bufio.NewScanner(reqR)
		scanner.Buffer(make([]byte, 0, 64*1024), maxWrapperLineBytes)
		scanner.Scan()
		respW.Close() // subprocess "exited": stdout closes with no response
	}()

	scanner := bufio.NewScanner(respR)
	scanner.Buffer(make([]byte, 0, 64*1024), maxWrapperLineBytes)
	c := &subprocessClient{started: true, enc: json.NewEncoder(reqW), scanner: scanner}

	_, err := c.roundTrip(context.Background(), "authenticate", nil)
	if err == nil || !strings.Contains(err.Error(), "closed") {
		t.Fatalf("roundTrip error = %v, want a subprocess-closed error", err)
	}
}

func TestSubprocessClient_RoundTrip_WrapperErrorPropagates(t *testing.T) {
	c := newFakeWrapperClient(t, func(cmd string, params json.RawMessage) wireResponsePayload {
		return fakeError("boom")
	})

	_, err := c.roundTrip(context.Background(), "authenticate", nil)
	if err == nil || !strings.Contains(err.Error(), "boom") {
		t.Fatalf("roundTrip error = %v, want it to mention %q", err, "boom")
	}
}

func TestSubprocessClient_RoundTrip_NotFoundWrapsErrNotFound(t *testing.T) {
	c := newFakeWrapperClient(t, func(cmd string, params json.RawMessage) wireResponsePayload {
		return fakeNotFoundError("API Error 404")
	})

	_, err := c.roundTrip(context.Background(), "call", nil)
	if !errors.Is(err, ErrNotFound) {
		t.Fatalf("roundTrip error = %v, want errors.Is(err, ErrNotFound)", err)
	}
	if !strings.Contains(err.Error(), "API Error 404") {
		t.Errorf("roundTrip error = %v, want it to still contain the original message", err)
	}
}

func TestSubprocessClient_RoundTrip_OrdinaryErrorDoesNotWrapErrNotFound(t *testing.T) {
	c := newFakeWrapperClient(t, func(cmd string, params json.RawMessage) wireResponsePayload {
		return fakeError("boom")
	})

	_, err := c.roundTrip(context.Background(), "call", nil)
	if errors.Is(err, ErrNotFound) {
		t.Fatalf("roundTrip error = %v, want errors.Is(err, ErrNotFound) to be false", err)
	}
}

func TestSubprocessClient_UpdateCredentials_ResetsStartedState(t *testing.T) {
	c := &subprocessClient{cfg: ClientConfig{GarminEmail: "old@example.com", GarminPassword: "old"}}
	c.started = true // simulate an already-spawned subprocess, no real cmd/pipes

	c.UpdateCredentials("new@example.com", "new")

	if c.cfg.GarminEmail != "new@example.com" || c.cfg.GarminPassword != "new" {
		t.Errorf("cfg after update = %+v, want new@example.com/new", c.cfg)
	}
	if c.started {
		t.Error("started should be reset to false so the next call respawns the subprocess")
	}
}

func TestSubprocessClient_Close_NoOpWhenNotStarted(t *testing.T) {
	c := &subprocessClient{}
	if err := c.Close(); err != nil {
		t.Errorf("Close on an unstarted client = %v, want nil", err)
	}
}

// TestSubprocessClient_Close_WaitsForStderrCopyGoroutine exercises close()
// against a real subprocess that writes to stderr, mirroring how
// ensureStarted wires up the stderr-copy goroutine. Per os/exec's
// StderrPipe docs it is incorrect to call Wait before all reads from the
// pipe have completed; this guards against close() calling cmd.Wait()
// before the copy goroutine has drained the pipe (which previously risked a
// race / truncated stderr / spurious "file already closed" errors).
func TestSubprocessClient_Close_WaitsForStderrCopyGoroutine(t *testing.T) {
	cmd := exec.Command("sh", "-c", "for i in 1 2 3 4 5; do echo line$i 1>&2; done; sleep 5")
	stderr, err := cmd.StderrPipe()
	if err != nil {
		t.Fatalf("StderrPipe: %v", err)
	}
	if err := cmd.Start(); err != nil {
		t.Fatalf("Start: %v", err)
	}

	stderrDone := make(chan struct{})
	go func() {
		io.Copy(io.Discard, stderr)
		close(stderrDone)
	}()

	c := &subprocessClient{started: true, cmd: cmd, stderrDone: stderrDone}

	done := make(chan error, 1)
	go func() { done <- c.close() }()

	select {
	case <-done:
		// close() returned -- since it killed the process and waited on
		// stderrDone before Wait-ing, this proves the ordering held without
		// deadlocking.
	case <-time.After(5 * time.Second):
		t.Fatal("close() did not return in time -- likely blocked waiting on stderrDone")
	}

	if c.stderrDone != nil {
		t.Error("stderrDone should be reset to nil after close()")
	}
}

func TestSubprocessClient_Authenticate_Success(t *testing.T) {
	c := newFakeWrapperClient(t, func(cmd string, params json.RawMessage) wireResponsePayload {
		if cmd != "authenticate" {
			t.Fatalf("unexpected cmd %q", cmd)
		}
		return fakeResult(authResultWire{Status: "success", Message: "Authenticated successfully."})
	})

	res, err := c.Authenticate(context.Background())
	if err != nil {
		t.Fatalf("Authenticate: %v", err)
	}
	if res.Status != AuthSuccess || res.Message != "Authenticated successfully." {
		t.Errorf("Authenticate result = %+v", res)
	}
}

func TestSubprocessClient_Authenticate_MFARequired(t *testing.T) {
	c := newFakeWrapperClient(t, func(cmd string, params json.RawMessage) wireResponsePayload {
		return fakeResult(authResultWire{Status: "mfa_required", Message: "MFA required. ..."})
	})

	res, err := c.Authenticate(context.Background())
	if err != nil {
		t.Fatalf("Authenticate: %v", err)
	}
	if res.Status != AuthMFARequired {
		t.Errorf("Authenticate status = %v, want AuthMFARequired", res.Status)
	}
}

func TestSubprocessClient_Authenticate_WrapperErrorPropagates(t *testing.T) {
	c := newFakeWrapperClient(t, func(cmd string, params json.RawMessage) wireResponsePayload {
		return fakeError("subprocess exploded")
	})

	_, err := c.Authenticate(context.Background())
	if err == nil || !strings.Contains(err.Error(), "subprocess exploded") {
		t.Fatalf("Authenticate error = %v, want it to mention the wrapper error", err)
	}
}

func TestSubprocessClient_CompleteMFA_SendsCodeAndReturnsStatus(t *testing.T) {
	var gotCode string
	c := newFakeWrapperClient(t, func(cmd string, params json.RawMessage) wireResponsePayload {
		if cmd != "complete_mfa" {
			t.Fatalf("unexpected cmd %q", cmd)
		}
		var p struct {
			Code string `json:"code"`
		}
		if err := json.Unmarshal(params, &p); err != nil {
			t.Fatalf("unmarshal params: %v", err)
		}
		gotCode = p.Code
		return fakeResult(authResultWire{Status: "success", Message: "MFA accepted. Authenticated successfully."})
	})

	res, err := c.CompleteMFA(context.Background(), "123456")
	if err != nil {
		t.Fatalf("CompleteMFA: %v", err)
	}
	if gotCode != "123456" {
		t.Errorf("code sent to wrapper = %q, want 123456", gotCode)
	}
	if res.Status != AuthSuccess {
		t.Errorf("CompleteMFA status = %v, want AuthSuccess", res.Status)
	}
}

func TestSubprocessClient_CompleteMFA_Failed(t *testing.T) {
	c := newFakeWrapperClient(t, func(cmd string, params json.RawMessage) wireResponsePayload {
		return fakeResult(authResultWire{Status: "failed", Message: "Authentication failed after MFA: bad code"})
	})

	res, err := c.CompleteMFA(context.Background(), "000000")
	if err != nil {
		t.Fatalf("CompleteMFA: %v", err)
	}
	if res.Status != AuthFailed {
		t.Errorf("CompleteMFA status = %v, want AuthFailed", res.Status)
	}
}

func TestSubprocessClient_GetActivities_UsesGarminconnectKwargNames(t *testing.T) {
	var gotMethod string
	var gotArgs map[string]any
	c := newFakeWrapperClient(t, func(cmd string, params json.RawMessage) wireResponsePayload {
		var p callParams
		if err := json.Unmarshal(params, &p); err != nil {
			t.Fatalf("unmarshal params: %v", err)
		}
		gotMethod, gotArgs = p.Method, p.Args
		return fakeResult([]map[string]any{
			{"activityId": float64(123), "activityType": map[string]any{"typeKey": "running"}},
		})
	})

	activities, err := c.GetActivities(context.Background(), "2026-07-01", "2026-07-25", 0)
	if err != nil {
		t.Fatalf("GetActivities: %v", err)
	}
	if gotMethod != "get_activities_by_date" {
		t.Errorf("method = %q, want get_activities_by_date", gotMethod)
	}
	if gotArgs["startdate"] != "2026-07-01" || gotArgs["enddate"] != "2026-07-25" {
		t.Errorf("args = %+v, want startdate/enddate matching garminconnect's real kwargs", gotArgs)
	}
	if len(activities) != 1 || activities[0].ActivityID != 123 {
		t.Fatalf("activities = %+v", activities)
	}
}

func TestSubprocessClient_GetActivities_AppliesLimitClientSide(t *testing.T) {
	c := newFakeWrapperClient(t, func(cmd string, params json.RawMessage) wireResponsePayload {
		raw := make([]map[string]any, 5)
		for i := range raw {
			raw[i] = map[string]any{"activityId": float64(i)}
		}
		return fakeResult(raw)
	})

	activities, err := c.GetActivities(context.Background(), "2026-07-01", "2026-07-25", 2)
	if err != nil {
		t.Fatalf("GetActivities: %v", err)
	}
	if len(activities) != 2 {
		t.Fatalf("len(activities) = %d, want 2", len(activities))
	}
}

func TestSubprocessClient_GetActivitySplits_ParsesLapDTOsEnvelope(t *testing.T) {
	var gotMethod string
	var gotArgs map[string]any
	c := newFakeWrapperClient(t, func(cmd string, params json.RawMessage) wireResponsePayload {
		var p callParams
		json.Unmarshal(params, &p)
		gotMethod, gotArgs = p.Method, p.Args
		return fakeResult(map[string]any{
			"activityId": float64(111),
			"lapDTOs":    []map[string]any{{"lapIndex": float64(1), "distance": float64(1000)}},
		})
	})

	splits, err := c.GetActivitySplits(context.Background(), 111)
	if err != nil {
		t.Fatalf("GetActivitySplits: %v", err)
	}
	if gotMethod != "get_activity_splits" || gotArgs["activity_id"] != "111" {
		t.Errorf("method/args = %q/%+v, want get_activity_splits with activity_id=\"111\"", gotMethod, gotArgs)
	}
	if splits.ActivityID != 111 || len(splits.Laps) != 1 || splits.Laps[0].LapIndex != 1 {
		t.Fatalf("splits = %+v", splits)
	}
}

func TestSubprocessClient_GetActivityDetails_ParsesRawTelemetry(t *testing.T) {
	c := newFakeWrapperClient(t, func(cmd string, params json.RawMessage) wireResponsePayload {
		var p callParams
		json.Unmarshal(params, &p)
		if p.Method != "get_activity_details" || p.Args["activity_id"] != "222" {
			t.Fatalf("unexpected call: %+v", p)
		}
		return fakeResult(map[string]any{
			"activityId":            float64(222),
			"metricDescriptors":     []map[string]any{{"key": "directHeartRate", "metricsIndex": float64(0)}},
			"activityDetailMetrics": []map[string]any{{"metrics": []any{float64(101)}}},
		})
	})

	details, err := c.GetActivityDetails(context.Background(), 222)
	if err != nil {
		t.Fatalf("GetActivityDetails: %v", err)
	}
	if details.ActivityID != 222 || len(details.MetricDescriptors) != 1 {
		t.Fatalf("details = %+v", details)
	}
}

func TestSubprocessClient_GetWorkoutByID_ParsesSegments(t *testing.T) {
	c := newFakeWrapperClient(t, func(cmd string, params json.RawMessage) wireResponsePayload {
		var p callParams
		json.Unmarshal(params, &p)
		if p.Method != "get_workout_by_id" || p.Args["workout_id"] != "333" {
			t.Fatalf("unexpected call: %+v", p)
		}
		return fakeResult(map[string]any{
			"workoutId":       float64(333),
			"workoutName":     "Tempo",
			"workoutSegments": []map[string]any{{"segmentOrder": float64(1), "workoutSteps": []any{}}},
		})
	})

	workout, err := c.GetWorkoutByID(context.Background(), 333)
	if err != nil {
		t.Fatalf("GetWorkoutByID: %v", err)
	}
	if workout.WorkoutID != 333 || workout.WorkoutName != "Tempo" || len(workout.Segments) != 1 {
		t.Fatalf("workout = %+v", workout)
	}
}

func TestSubprocessClient_RoundTrip_LogsCallWithResultPreview(t *testing.T) {
	c := newFakeWrapperClient(t, func(cmd string, params json.RawMessage) wireResponsePayload {
		return fakeResult(authResultWire{Status: "mfa_required", Message: "MFA required."})
	})

	var buf bytes.Buffer
	logger := slog.New(slog.NewJSONHandler(&buf, nil))
	ctx := applog.WithLogger(context.Background(), logger)

	if _, err := c.Authenticate(ctx); err != nil {
		t.Fatalf("Authenticate: %v", err)
	}

	var entry map[string]any
	if err := json.Unmarshal(buf.Bytes(), &entry); err != nil {
		t.Fatalf("log output is not valid JSON: %v (%q)", err, buf.String())
	}
	if entry["msg"] != "Garmin wrapper call" {
		t.Errorf("msg = %v, want \"Garmin wrapper call\"", entry["msg"])
	}
	if entry["cmd"] != "authenticate" {
		t.Errorf("cmd = %v, want authenticate", entry["cmd"])
	}
	preview, _ := entry["result"].(string)
	if !strings.Contains(preview, "mfa_required") {
		t.Errorf("result = %q, want it to contain mfa_required", preview)
	}
	if _, hasError := entry["error"]; hasError {
		t.Errorf("expected no error field on a successful call, got %v", entry["error"])
	}
}

func TestSubprocessClient_RoundTrip_LogsFailedCallAtErrorLevel(t *testing.T) {
	c := newFakeWrapperClient(t, func(cmd string, params json.RawMessage) wireResponsePayload {
		return fakeError("boom")
	})

	var buf bytes.Buffer
	logger := slog.New(slog.NewJSONHandler(&buf, nil))
	ctx := applog.WithLogger(context.Background(), logger)

	if _, err := c.Authenticate(ctx); err == nil {
		t.Fatal("expected Authenticate to return an error")
	}

	var entry map[string]any
	if err := json.Unmarshal(buf.Bytes(), &entry); err != nil {
		t.Fatalf("log output is not valid JSON: %v (%q)", err, buf.String())
	}
	if entry["level"] != "ERROR" {
		t.Errorf("level = %v, want ERROR for a failed call", entry["level"])
	}
	if errMsg, _ := entry["error"].(string); !strings.Contains(errMsg, "boom") {
		t.Errorf("error field = %q, want it to mention \"boom\"", errMsg)
	}
}