package api

import (
	"bytes"
	"encoding/json"
	"net/http"
	"net/http/httptest"
	"testing"
	"time"

	"github.com/thepeterstone/claudomator/internal/event"
	"github.com/thepeterstone/claudomator/internal/story"
	"github.com/thepeterstone/claudomator/internal/task"
)

func TestServer_CreateStory_AndGetStory(t *testing.T) {
	srv, _ := testServer(t)

	body, _ := json.Marshal(map[string]any{
		"name":                "Add login page",
		"status":              "DISCOVERY",
		"epic_id":             "epic-1",
		"acceptance_criteria": []string{"User can log in"},
	})
	req := httptest.NewRequest("POST", "/api/stories", bytes.NewReader(body))
	w := httptest.NewRecorder()
	srv.Handler().ServeHTTP(w, req)
	if w.Code != http.StatusCreated {
		t.Fatalf("create: expected 201, got %d: %s", w.Code, w.Body.String())
	}
	var created story.Story
	if err := json.Unmarshal(w.Body.Bytes(), &created); err != nil {
		t.Fatalf("decode create response: %v", err)
	}
	if created.ID == "" {
		t.Fatal("expected server-assigned ID")
	}

	req = httptest.NewRequest("GET", "/api/stories/"+created.ID, nil)
	w = httptest.NewRecorder()
	srv.Handler().ServeHTTP(w, req)
	if w.Code != http.StatusOK {
		t.Fatalf("get: expected 200, got %d: %s", w.Code, w.Body.String())
	}
	var got story.Story
	if err := json.Unmarshal(w.Body.Bytes(), &got); err != nil {
		t.Fatalf("decode get response: %v", err)
	}
	if got.Name != "Add login page" {
		t.Errorf("Name: want %q, got %q", "Add login page", got.Name)
	}
	if got.EpicID != "epic-1" {
		t.Errorf("EpicID: want epic-1, got %q", got.EpicID)
	}
	if len(got.AcceptanceCriteria) != 1 || got.AcceptanceCriteria[0] != "User can log in" {
		t.Errorf("AcceptanceCriteria: want [User can log in], got %+v", got.AcceptanceCriteria)
	}
}

func TestServer_CreateStory_MissingName_Returns400(t *testing.T) {
	srv, _ := testServer(t)
	req := httptest.NewRequest("POST", "/api/stories", bytes.NewReader([]byte(`{}`)))
	w := httptest.NewRecorder()
	srv.Handler().ServeHTTP(w, req)
	if w.Code != http.StatusBadRequest {
		t.Fatalf("expected 400, got %d: %s", w.Code, w.Body.String())
	}
}

func TestServer_GetStory_NotFound(t *testing.T) {
	srv, _ := testServer(t)
	req := httptest.NewRequest("GET", "/api/stories/does-not-exist", nil)
	w := httptest.NewRecorder()
	srv.Handler().ServeHTTP(w, req)
	if w.Code != http.StatusNotFound {
		t.Fatalf("expected 404, got %d: %s", w.Code, w.Body.String())
	}
}

func TestServer_ListStories_FiltersByStatusAndEpic(t *testing.T) {
	srv, store := testServer(t)
	for _, st := range []*story.Story{
		{ID: "s1", EpicID: "epic-a", Name: "one", Status: "DISCOVERY"},
		{ID: "s2", EpicID: "epic-a", Name: "two", Status: "IN_PROGRESS"},
		{ID: "s3", EpicID: "epic-b", Name: "three", Status: "DISCOVERY"},
	} {
		if err := store.CreateStory(st); err != nil {
			t.Fatal(err)
		}
	}

	req := httptest.NewRequest("GET", "/api/stories?epic_id=epic-a&status=DISCOVERY", nil)
	w := httptest.NewRecorder()
	srv.Handler().ServeHTTP(w, req)
	if w.Code != http.StatusOK {
		t.Fatalf("expected 200, got %d: %s", w.Code, w.Body.String())
	}
	var got []story.Story
	if err := json.Unmarshal(w.Body.Bytes(), &got); err != nil {
		t.Fatalf("decode: %v", err)
	}
	if len(got) != 1 || got[0].ID != "s1" {
		t.Fatalf("want exactly [s1], got %+v", got)
	}
}

func TestServer_UpdateStory_UnvalidatedStatusPassthrough(t *testing.T) {
	srv, store := testServer(t)
	if err := store.CreateStory(&story.Story{ID: "s1", Name: "original", Status: "DISCOVERY"}); err != nil {
		t.Fatal(err)
	}

	// A nonsensical status jump must still be accepted — this phase performs
	// no status-machine validation on stories.
	body, _ := json.Marshal(map[string]any{
		"name":         "updated",
		"status":       "DONE",
		"root_task_id": "task-x",
	})
	req := httptest.NewRequest("PUT", "/api/stories/s1", bytes.NewReader(body))
	w := httptest.NewRecorder()
	srv.Handler().ServeHTTP(w, req)
	if w.Code != http.StatusOK {
		t.Fatalf("expected 200, got %d: %s", w.Code, w.Body.String())
	}
	var got story.Story
	if err := json.Unmarshal(w.Body.Bytes(), &got); err != nil {
		t.Fatalf("decode: %v", err)
	}
	if got.Status != "DONE" {
		t.Errorf("Status: want DONE (unvalidated passthrough), got %q", got.Status)
	}
	if got.RootTaskID != "task-x" {
		t.Errorf("RootTaskID: want task-x, got %q", got.RootTaskID)
	}
	if got.ID != "s1" {
		t.Errorf("ID must not change via body: got %q", got.ID)
	}
}

func TestServer_UpdateStory_NotFound(t *testing.T) {
	srv, _ := testServer(t)
	req := httptest.NewRequest("PUT", "/api/stories/does-not-exist", bytes.NewReader([]byte(`{"name":"x"}`)))
	w := httptest.NewRecorder()
	srv.Handler().ServeHTTP(w, req)
	if w.Code != http.StatusNotFound {
		t.Fatalf("expected 404, got %d: %s", w.Code, w.Body.String())
	}
}

func makeTreeTestTask(id, parentID string, dependsOn []string) *task.Task {
	now := time.Now().UTC()
	if dependsOn == nil {
		dependsOn = []string{}
	}
	return &task.Task{
		ID:           id,
		Name:         "Task " + id,
		Agent:        task.AgentConfig{Type: "claude", Instructions: "x"},
		Priority:     task.PriorityNormal,
		Retry:        task.RetryConfig{MaxAttempts: 1, Backoff: "linear"},
		Tags:         []string{},
		DependsOn:    dependsOn,
		ParentTaskID: parentID,
		State:        task.StatePending,
		CreatedAt:    now,
		UpdatedAt:    now,
	}
}

// TestServer_StoryTaskTree_WalksParentAndDependsOnEdges constructs a small
// task tree by hand: a root task, a parent_task_id child of the root, and a
// separate task (not a parent_task_id child of anything) whose
// depends_on_json points at the root. Confirms the task-tree endpoint
// discovers all three via the combination of ListSubtasks (parent_task_id)
// and ListDependents (depends_on_json) traversal.
func TestServer_StoryTaskTree_WalksParentAndDependsOnEdges(t *testing.T) {
	srv, store := testServer(t)

	root := makeTreeTestTask("tt-root", "", nil)
	child := makeTreeTestTask("tt-child", "tt-root", nil)
	sibling := makeTreeTestTask("tt-sibling", "", []string{"tt-root"})
	for _, tk := range []*task.Task{root, child, sibling} {
		if err := store.CreateTask(tk); err != nil {
			t.Fatalf("CreateTask(%s): %v", tk.ID, err)
		}
	}

	if err := store.CreateStory(&story.Story{ID: "story-1", Name: "story", Status: "IN_PROGRESS", RootTaskID: "tt-root"}); err != nil {
		t.Fatal(err)
	}

	req := httptest.NewRequest("GET", "/api/stories/story-1/task-tree", nil)
	w := httptest.NewRecorder()
	srv.Handler().ServeHTTP(w, req)
	if w.Code != http.StatusOK {
		t.Fatalf("expected 200, got %d: %s", w.Code, w.Body.String())
	}

	var got taskTreeResponse
	if err := json.Unmarshal(w.Body.Bytes(), &got); err != nil {
		t.Fatalf("decode: %v", err)
	}
	if got.StoryID != "story-1" {
		t.Errorf("StoryID: want story-1, got %q", got.StoryID)
	}
	if got.RootTaskID != "tt-root" {
		t.Errorf("RootTaskID: want tt-root, got %q", got.RootTaskID)
	}
	if len(got.Nodes) != 3 {
		t.Fatalf("want 3 nodes, got %d: %+v", len(got.Nodes), got.Nodes)
	}

	byID := map[string]taskTreeNode{}
	for _, n := range got.Nodes {
		byID[n.ID] = n
	}
	if _, ok := byID["tt-root"]; !ok {
		t.Error("missing tt-root node")
	}
	childNode, ok := byID["tt-child"]
	if !ok {
		t.Fatal("missing tt-child node")
	}
	if childNode.ParentTaskID != "tt-root" {
		t.Errorf("tt-child.ParentTaskID: want tt-root, got %q", childNode.ParentTaskID)
	}
	siblingNode, ok := byID["tt-sibling"]
	if !ok {
		t.Fatal("missing tt-sibling node")
	}
	if len(siblingNode.DependsOn) != 1 || siblingNode.DependsOn[0] != "tt-root" {
		t.Errorf("tt-sibling.DependsOn: want [tt-root], got %+v", siblingNode.DependsOn)
	}
	for _, n := range got.Nodes {
		if n.State == "" {
			t.Errorf("node %s: expected non-empty state", n.ID)
		}
		if n.AgentType != "claude" {
			t.Errorf("node %s: AgentType = %q, want claude", n.ID, n.AgentType)
		}
	}
}

// TestServer_StoryTaskTree_EmptyWhenNoRootTask confirms an unset
// root_task_id returns an empty node list, not an error.
func TestServer_StoryTaskTree_EmptyWhenNoRootTask(t *testing.T) {
	srv, store := testServer(t)
	if err := store.CreateStory(&story.Story{ID: "story-empty", Name: "story", Status: "DISCOVERY"}); err != nil {
		t.Fatal(err)
	}

	req := httptest.NewRequest("GET", "/api/stories/story-empty/task-tree", nil)
	w := httptest.NewRecorder()
	srv.Handler().ServeHTTP(w, req)
	if w.Code != http.StatusOK {
		t.Fatalf("expected 200, got %d: %s", w.Code, w.Body.String())
	}
	var got taskTreeResponse
	if err := json.Unmarshal(w.Body.Bytes(), &got); err != nil {
		t.Fatalf("decode: %v", err)
	}
	if got.RootTaskID != "" {
		t.Errorf("RootTaskID: want empty, got %q", got.RootTaskID)
	}
	if len(got.Nodes) != 0 {
		t.Fatalf("want empty node list, got %+v", got.Nodes)
	}
}

func TestServer_StoryTaskTree_UnknownStory_Returns404(t *testing.T) {
	srv, _ := testServer(t)
	req := httptest.NewRequest("GET", "/api/stories/does-not-exist/task-tree", nil)
	w := httptest.NewRecorder()
	srv.Handler().ServeHTTP(w, req)
	if w.Code != http.StatusNotFound {
		t.Fatalf("expected 404, got %d: %s", w.Code, w.Body.String())
	}
}

// TestServer_AcceptStory_SucceedsFromReviewReady is verification item (e)
// from the Phase 7b task description: POST /api/stories/{id}/accept
// transitions REVIEW_READY -> DONE and emits a KindHumanAccepted event
// attached to the story's ID.
func TestServer_AcceptStory_SucceedsFromReviewReady(t *testing.T) {
	srv, store := testServer(t)
	if err := store.CreateStory(&story.Story{ID: "s1", Name: "story", Status: "REVIEW_READY"}); err != nil {
		t.Fatal(err)
	}

	req := httptest.NewRequest("POST", "/api/stories/s1/accept", nil)
	w := httptest.NewRecorder()
	srv.Handler().ServeHTTP(w, req)
	if w.Code != http.StatusOK {
		t.Fatalf("expected 200, got %d: %s", w.Code, w.Body.String())
	}

	got, err := store.GetStory("s1")
	if err != nil {
		t.Fatal(err)
	}
	if got.Status != "DONE" {
		t.Errorf("Status: want DONE, got %q", got.Status)
	}

	evs, err := store.ListEvents("s1", 0)
	if err != nil {
		t.Fatal(err)
	}
	var found bool
	for _, e := range evs {
		if e.Kind == event.KindHumanAccepted {
			found = true
			var payload struct {
				StoryID string `json:"story_id"`
				From    string `json:"from"`
				To      string `json:"to"`
			}
			if err := json.Unmarshal(e.Payload, &payload); err != nil {
				t.Fatalf("unmarshal payload: %v", err)
			}
			if payload.StoryID != "s1" || payload.From != "REVIEW_READY" || payload.To != "DONE" {
				t.Errorf("unexpected payload: %+v", payload)
			}
		}
	}
	if !found {
		t.Error("expected a KindHumanAccepted event attached to the story's event stream")
	}
}

// TestServer_AcceptStory_FailsFromOtherStatuses is the other half of
// verification item (e): accept must be rejected (409) from any status other
// than REVIEW_READY.
func TestServer_AcceptStory_FailsFromOtherStatuses(t *testing.T) {
	for _, status := range []string{"DISCOVERY", "VALIDATING", "NEEDS_FIX", "DONE", "IN_PROGRESS"} {
		t.Run(status, func(t *testing.T) {
			srv, store := testServer(t)
			id := "s-" + status
			if err := store.CreateStory(&story.Story{ID: id, Name: "story", Status: status}); err != nil {
				t.Fatal(err)
			}

			req := httptest.NewRequest("POST", "/api/stories/"+id+"/accept", nil)
			w := httptest.NewRecorder()
			srv.Handler().ServeHTTP(w, req)
			if w.Code != http.StatusConflict {
				t.Fatalf("expected 409, got %d: %s", w.Code, w.Body.String())
			}

			got, err := store.GetStory(id)
			if err != nil {
				t.Fatal(err)
			}
			if got.Status != status {
				t.Errorf("status must not change on rejected accept: want %q, got %q", status, got.Status)
			}
		})
	}
}

func TestServer_AcceptStory_NotFound(t *testing.T) {
	srv, _ := testServer(t)
	req := httptest.NewRequest("POST", "/api/stories/does-not-exist/accept", nil)
	w := httptest.NewRecorder()
	srv.Handler().ServeHTTP(w, req)
	if w.Code != http.StatusNotFound {
		t.Fatalf("expected 404, got %d: %s", w.Code, w.Body.String())
	}
}

// TestServer_ListStoryEvents_ReturnsEvalVerdictAndArbitrationEvents proves
// GET /api/stories/{id}/events surfaces events written against the story's
// own ID (not any task's ID) — the attachment point
// internal/scheduler.StoryOrchestrator uses for KindEvalVerdict/
// KindArbitrationDecided.
func TestServer_ListStoryEvents_ReturnsEvalVerdictAndArbitrationEvents(t *testing.T) {
	srv, store := testServer(t)
	if err := store.CreateStory(&story.Story{ID: "s1", Name: "story", Status: "VALIDATING"}); err != nil {
		t.Fatal(err)
	}
	if err := store.CreateEvent(&event.Event{TaskID: "s1", Kind: event.KindEvalVerdict, Actor: event.ActorSystem, Payload: []byte(`{"role":"evaluator_quality"}`)}); err != nil {
		t.Fatal(err)
	}

	req := httptest.NewRequest("GET", "/api/stories/s1/events", nil)
	w := httptest.NewRecorder()
	srv.Handler().ServeHTTP(w, req)
	if w.Code != http.StatusOK {
		t.Fatalf("expected 200, got %d: %s", w.Code, w.Body.String())
	}
	var got []event.Event
	if err := json.Unmarshal(w.Body.Bytes(), &got); err != nil {
		t.Fatalf("decode: %v", err)
	}
	if len(got) != 1 || got[0].Kind != event.KindEvalVerdict {
		t.Fatalf("want 1 eval_verdict event, got %+v", got)
	}
}

func TestServer_ListStoryEvents_UnknownStory_Returns404(t *testing.T) {
	srv, _ := testServer(t)
	req := httptest.NewRequest("GET", "/api/stories/does-not-exist/events", nil)
	w := httptest.NewRecorder()
	srv.Handler().ServeHTTP(w, req)
	if w.Code != http.StatusNotFound {
		t.Fatalf("expected 404, got %d: %s", w.Code, w.Body.String())
	}
}