package api

import (
	"encoding/json"
	"net/http"
	"net/http/httptest"
	"strings"
	"testing"

	"github.com/go-chi/chi/v5"
)

func newRevisionRouter(s *Server) http.Handler {
	r := chi.NewRouter()
	r.Route("/api/items/{partNumber}", func(r chi.Router) {
		r.Get("/revisions", s.HandleListRevisions)
		r.Get("/revisions/compare", s.HandleCompareRevisions)
		r.Get("/revisions/{revision}", s.HandleGetRevision)
		r.Post("/revisions", s.HandleCreateRevision)
		r.Patch("/revisions/{revision}", s.HandleUpdateRevision)
		r.Post("/revisions/{revision}/rollback", s.HandleRollbackRevision)
	})
	return r
}

func TestHandleListRevisions(t *testing.T) {
	s := newTestServer(t)
	router := newRevisionRouter(s)

	createItemDirect(t, s, "REV-API-001", "revision list", nil)

	req := httptest.NewRequest("GET", "/api/items/REV-API-001/revisions", nil)
	w := httptest.NewRecorder()
	router.ServeHTTP(w, req)

	if w.Code != http.StatusOK {
		t.Fatalf("status: got %d, want %d; body: %s", w.Code, http.StatusOK, w.Body.String())
	}

	var revisions []RevisionResponse
	if err := json.Unmarshal(w.Body.Bytes(), &revisions); err != nil {
		t.Fatalf("decoding response: %v", err)
	}
	if len(revisions) != 1 {
		t.Errorf("expected 1 revision (initial), got %d", len(revisions))
	}
}

func TestHandleListRevisionsNotFound(t *testing.T) {
	s := newTestServer(t)
	router := newRevisionRouter(s)

	req := httptest.NewRequest("GET", "/api/items/NOEXIST/revisions", nil)
	w := httptest.NewRecorder()
	router.ServeHTTP(w, req)

	if w.Code != http.StatusNotFound {
		t.Errorf("status: got %d, want %d", w.Code, http.StatusNotFound)
	}
}

func TestHandleGetRevision(t *testing.T) {
	s := newTestServer(t)
	router := newRevisionRouter(s)

	createItemDirect(t, s, "REVGET-001", "get revision", nil)

	req := httptest.NewRequest("GET", "/api/items/REVGET-001/revisions/1", nil)
	w := httptest.NewRecorder()
	router.ServeHTTP(w, req)

	if w.Code != http.StatusOK {
		t.Fatalf("status: got %d, want %d; body: %s", w.Code, http.StatusOK, w.Body.String())
	}

	var rev RevisionResponse
	if err := json.Unmarshal(w.Body.Bytes(), &rev); err != nil {
		t.Fatalf("decoding response: %v", err)
	}
	if rev.RevisionNumber != 1 {
		t.Errorf("revision_number: got %d, want 1", rev.RevisionNumber)
	}
}

func TestHandleGetRevisionNotFound(t *testing.T) {
	s := newTestServer(t)
	router := newRevisionRouter(s)

	createItemDirect(t, s, "REVNF-001", "rev not found", nil)

	req := httptest.NewRequest("GET", "/api/items/REVNF-001/revisions/99", nil)
	w := httptest.NewRecorder()
	router.ServeHTTP(w, req)

	if w.Code != http.StatusNotFound {
		t.Errorf("status: got %d, want %d", w.Code, http.StatusNotFound)
	}
}

func TestHandleCreateRevision(t *testing.T) {
	s := newTestServer(t)
	router := newRevisionRouter(s)

	createItemDirect(t, s, "REVCR-001", "create revision", nil)

	body := `{"properties":{"material":"steel"},"comment":"added material"}`
	req := authRequest(httptest.NewRequest("POST", "/api/items/REVCR-001/revisions", strings.NewReader(body)))
	req.Header.Set("Content-Type", "application/json")
	w := httptest.NewRecorder()
	router.ServeHTTP(w, req)

	if w.Code != http.StatusCreated {
		t.Fatalf("status: got %d, want %d; body: %s", w.Code, http.StatusCreated, w.Body.String())
	}

	var rev RevisionResponse
	if err := json.Unmarshal(w.Body.Bytes(), &rev); err != nil {
		t.Fatalf("decoding response: %v", err)
	}
	if rev.RevisionNumber != 2 {
		t.Errorf("revision_number: got %d, want 2", rev.RevisionNumber)
	}
}

func TestHandleUpdateRevision(t *testing.T) {
	s := newTestServer(t)
	router := newRevisionRouter(s)

	createItemDirect(t, s, "REVUP-001", "update revision", nil)

	body := `{"status":"released","labels":["production"]}`
	req := authRequest(httptest.NewRequest("PATCH", "/api/items/REVUP-001/revisions/1", strings.NewReader(body)))
	req.Header.Set("Content-Type", "application/json")
	w := httptest.NewRecorder()
	router.ServeHTTP(w, req)

	if w.Code != http.StatusOK {
		t.Fatalf("status: got %d, want %d; body: %s", w.Code, http.StatusOK, w.Body.String())
	}

	var rev RevisionResponse
	if err := json.Unmarshal(w.Body.Bytes(), &rev); err != nil {
		t.Fatalf("decoding response: %v", err)
	}
	if rev.Status != "released" {
		t.Errorf("status: got %q, want %q", rev.Status, "released")
	}
	if len(rev.Labels) != 1 || rev.Labels[0] != "production" {
		t.Errorf("labels: got %v, want [production]", rev.Labels)
	}
}

func TestHandleCompareRevisions(t *testing.T) {
	s := newTestServer(t)
	router := newRevisionRouter(s)

	// Create item with properties, then create second revision with changed properties
	cost := 10.0
	createItemDirect(t, s, "REVCMP-001", "compare revisions", &cost)

	body := `{"properties":{"standard_cost":20,"material":"aluminum"},"comment":"updated cost"}`
	req := authRequest(httptest.NewRequest("POST", "/api/items/REVCMP-001/revisions", strings.NewReader(body)))
	req.Header.Set("Content-Type", "application/json")
	w := httptest.NewRecorder()
	router.ServeHTTP(w, req)
	if w.Code != http.StatusCreated {
		t.Fatalf("create rev 2: status %d; body: %s", w.Code, w.Body.String())
	}

	// Compare rev 1 vs rev 2
	req = httptest.NewRequest("GET", "/api/items/REVCMP-001/revisions/compare?from=1&to=2", nil)
	w = httptest.NewRecorder()
	router.ServeHTTP(w, req)

	if w.Code != http.StatusOK {
		t.Fatalf("status: got %d, want %d; body: %s", w.Code, http.StatusOK, w.Body.String())
	}

	var diff RevisionDiffResponse
	if err := json.Unmarshal(w.Body.Bytes(), &diff); err != nil {
		t.Fatalf("decoding response: %v", err)
	}
	if diff.FromRevision != 1 || diff.ToRevision != 2 {
		t.Errorf("revisions: got from=%d to=%d, want from=1 to=2", diff.FromRevision, diff.ToRevision)
	}
}

func TestHandleRollbackRevision(t *testing.T) {
	s := newTestServer(t)
	router := newRevisionRouter(s)

	createItemDirect(t, s, "REVRB-001", "rollback test", nil)

	// Create rev 2
	body := `{"properties":{"version":"v2"},"comment":"version 2"}`
	req := authRequest(httptest.NewRequest("POST", "/api/items/REVRB-001/revisions", strings.NewReader(body)))
	req.Header.Set("Content-Type", "application/json")
	w := httptest.NewRecorder()
	router.ServeHTTP(w, req)
	if w.Code != http.StatusCreated {
		t.Fatalf("create rev 2: status %d; body: %s", w.Code, w.Body.String())
	}

	// Rollback to rev 1 — should create rev 3
	body = `{"comment":"rolling back"}`
	req = authRequest(httptest.NewRequest("POST", "/api/items/REVRB-001/revisions/1/rollback", strings.NewReader(body)))
	req.Header.Set("Content-Type", "application/json")
	w = httptest.NewRecorder()
	router.ServeHTTP(w, req)

	if w.Code != http.StatusCreated {
		t.Fatalf("status: got %d, want %d; body: %s", w.Code, http.StatusCreated, w.Body.String())
	}

	var rev RevisionResponse
	if err := json.Unmarshal(w.Body.Bytes(), &rev); err != nil {
		t.Fatalf("decoding response: %v", err)
	}
	if rev.RevisionNumber != 3 {
		t.Errorf("revision_number: got %d, want 3", rev.RevisionNumber)
	}
}