package app

import (
	"context"
	"encoding/hex"
	"encoding/json"
	"net/http"
	"net/http/httptest"
	"reflect"
	"strings"
	"testing"

	"finance-duck/internal/analytics"
	"finance-duck/internal/classification"
	"finance-duck/internal/domain"
)

func testApp(t *testing.T) (*App, State) {
	t.Helper()
	t.Setenv("OPENROUTER_API_KEY", "")
	t.Setenv("ENABLEBANKING_APP_ID", "")
	t.Setenv("ENABLEBANKING_KEY_FILE", "")
	t.Setenv("ENABLEBANKING_REDIRECT_URL", "")
	a, err := Open(t.TempDir())
	if err != nil {
		t.Fatal(err)
	}
	t.Cleanup(func() { a.Close() })
	s, err := a.Snapshot(context.Background())
	if err != nil {
		t.Fatal(err)
	}
	s, err = a.Mutate(context.Background(), s.Revision, func(d *domain.Dataset) error {
		d.Accounts = append(d.Accounts, domain.Account{ID: "n26", DisplayName: "N26", Currency: "EUR", Active: true})
		d.Categories = append(d.Categories, domain.Category{ID: "groceries", Name: "Groceries", ParentID: "cat_expenses", Kind: "expense"})
		d.Tags = append(d.Tags, domain.Tag{ID: "home", Name: "home"})
		return nil
	})
	if err != nil {
		t.Fatal(err)
	}
	return a, s
}
func sampleFacts(description, date string, amount domain.Money) domain.Facts {
	return domain.Facts{Source: "test", AccountID: "n26", BookingDate: date, Amount: amount, Currency: "EUR", RawDescription: description, ExternalID: hex.EncodeToString([]byte(description))}
}
func seed(t *testing.T, a *App, s State) State {
	t.Helper()
	a.mu.Lock()
	result, err := a.importFacts(context.Background(), s, []domain.Facts{sampleFacts("REWE", "2026-09-08", "-42.80"), sampleFacts("EDEKA", "2026-09-09", "-19.30")})
	a.mu.Unlock()
	if err != nil {
		t.Fatal(err)
	}
	return result.State
}
func TestFailedClassificationStillImportsAndRetryIsIdempotent(t *testing.T) {
	a, s := testApp(t)
	mock := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) { w.WriteHeader(http.StatusServiceUnavailable) }))
	defer mock.Close()
	a.classifier = classification.Client{APIKey: "test", Model: "test/model", BaseURL: mock.URL}
	s = seed(t, a, s)
	if len(s.Data.Transactions) != 2 {
		t.Fatalf("lost imported transactions: %d", len(s.Data.Transactions))
	}
	for _, tx := range s.Data.Transactions {
		if tx.Enrichment.CategoryID != domain.ExpenseFallback || tx.Enrichment.Classification.Error == "" {
			t.Fatalf("missing fallback error: %+v", tx.Enrichment)
		}
	}
	before := domain.Clone(s.Data)
	a.mu.Lock()
	again, err := a.importFacts(context.Background(), s, []domain.Facts{sampleFacts("REWE", "2026-09-08", "-42.80"), sampleFacts("EDEKA", "2026-09-09", "-19.30")})
	a.mu.Unlock()
	if err != nil {
		t.Fatal(err)
	}
	if again.Imported != 0 || !reflect.DeepEqual(before, again.State.Data) {
		t.Fatal("retry changed the canonical financial dataset")
	}
	dash, err := a.Dashboard(context.Background(), analytics.Filter{})
	if err != nil {
		t.Fatal(err)
	}
	if len(dash.Totals) != 1 || dash.Totals[0].Expenses != "62.1000" {
		t.Fatalf("import not visible in analytics: %+v", dash.Totals)
	}
}
func mockClassifier(t *testing.T, a *App, inspect ...func(*http.Request)) {
	t.Helper()
	mock := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		for _, check := range inspect {
			check(r)
		}
		var req struct {
			Messages []struct {
				Content string `json:"content"`
			} `json:"messages"`
		}
		if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
			t.Error(err)
			w.WriteHeader(400)
			return
		}
		var prompt struct {
			Categories []struct{ ID, Name string } `json:"categories"`
		}
		if len(req.Messages) != 2 || json.Unmarshal([]byte(req.Messages[1].Content), &prompt) != nil {
			w.WriteHeader(400)
			return
		}
		category := ""
		for _, c := range prompt.Categories {
			if strings.Contains(strings.ToLower(c.Name), "groceries") {
				category = c.ID
			}
		}
		content, _ := json.Marshal(map[string]any{"merchant_id": nil, "new_merchant": "REWE", "category_id": category, "tag_ids": []string{}})
		json.NewEncoder(w).Encode(map[string]any{"choices": []any{map[string]any{"finish_reason": "stop", "message": map[string]any{"content": string(content)}}}})
	}))
	t.Cleanup(mock.Close)
	a.classifier = classification.Client{APIKey: "test", Model: "test/model", BaseURL: mock.URL}
}
func TestPreviewIsReadOnlySelectedApplyPreservesFactsAndOtherFields(t *testing.T) {
	a, s := testApp(t)
	s = seed(t, a, s)
	s, err := a.Mutate(context.Background(), s.Revision, func(d *domain.Dataset) error {
		for i := range d.Transactions {
			d.Transactions[i].Enrichment.TagIDs = []string{"home"}
		}
		return nil
	})
	if err != nil {
		t.Fatal(err)
	}
	mockClassifier(t, a)
	before := domain.Clone(s.Data)
	preview, err := a.Preview(context.Background(), PreviewRequest{Revision: s.Revision, From: "2026-09-01", To: "2026-09-30", Model: "improved/model", Fields: Fields{Category: true}})
	if err != nil {
		t.Fatal(err)
	}
	if len(preview.Changes) != 2 || len(preview.Errors) != 0 {
		t.Fatalf("unexpected preview: %+v", preview)
	}
	untouched, err := a.Snapshot(context.Background())
	if err != nil {
		t.Fatal(err)
	}
	if !reflect.DeepEqual(before, untouched.Data) {
		t.Fatal("preview mutated canonical records")
	}
	id := preview.Changes[0].ID
	applied, err := a.ApplyPreview(context.Background(), preview.ID, preview.Revision, []string{id})
	if err != nil {
		t.Fatal(err)
	}
	if len(applied.Data.Merchants) != len(before.Merchants) {
		t.Fatal("category-only reclassification created merchants")
	}
	for i, tx := range applied.Data.Transactions {
		if !reflect.DeepEqual(tx.Facts, before.Transactions[i].Facts) {
			t.Fatal("financial facts changed")
		}
		if !reflect.DeepEqual(tx.Enrichment.TagIDs, before.Transactions[i].Enrichment.TagIDs) {
			t.Fatal("unselected tags changed")
		}
		if tx.Facts.ID == id {
			if tx.Enrichment.CategoryID != "groceries" || tx.Enrichment.Classification.Model != "improved/model" {
				t.Fatal("selected category did not change")
			}
		} else if !reflect.DeepEqual(tx.Enrichment, before.Transactions[i].Enrichment) {
			t.Fatal("unselected transaction changed")
		}
	}
	if _, err = a.ApplyPreview(context.Background(), preview.ID, preview.Revision, []string{id}); err == nil {
		t.Fatal("consumed preview applied twice")
	}
}
func TestStalePreviewCannotOverwriteManualCorrection(t *testing.T) {
	a, s := testApp(t)
	s = seed(t, a, s)
	mockClassifier(t, a)
	p, err := a.Preview(context.Background(), PreviewRequest{Revision: s.Revision, From: "2026-09-01", To: "2026-09-30", Model: "test/model", Fields: Fields{Category: true}})
	if err != nil {
		t.Fatal(err)
	}
	if len(p.Changes) != 2 {
		t.Fatalf("expected category changes before stale apply: %+v", p)
	}
	s, err = a.Mutate(context.Background(), s.Revision, func(d *domain.Dataset) error { d.Transactions[0].Enrichment.TagIDs = []string{"home"}; return nil })
	if err != nil {
		t.Fatal(err)
	}
	if _, err = a.ApplyPreview(context.Background(), p.ID, p.Revision, []string{p.Changes[0].ID}); err == nil {
		t.Fatal("stale preview overwrote manual edit")
	}
	after, err := a.Snapshot(context.Background())
	if err != nil {
		t.Fatal(err)
	}
	if !reflect.DeepEqual(s.Data, after.Data) {
		t.Fatal("stale apply partially changed records")
	}
}