package app

import (
	"context"
	"encoding/hex"
	"encoding/json"
	"errors"
	"net/http"
	"net/http/httptest"
	"os"
	"path/filepath"
	"reflect"
	"strings"
	"sync/atomic"
	"testing"
	"time"

	"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")}, nil)
	a.mu.Unlock()
	if err != nil {
		t.Fatal(err)
	}
	return result.State
}

// A released binary wrote include_amount into config.toml. Refusing it on
// startup made every upgraded deployment crash-loop against its own settings
// file, so a retired key must load and then disappear on the next save.
func TestRetiredSettingLoadsAndIsRewrittenAwayButTyposStillFail(t *testing.T) {
	t.Setenv("OPENROUTER_API_KEY", "")
	t.Setenv("ENABLEBANKING_APP_ID", "")
	dir := t.TempDir()
	path := filepath.Join(dir, "config.toml")
	if err := os.WriteFile(path, []byte("classification_model = \"old/model\"\ninclude_amount = true\nclassify_on_import = false\n"), 0600); err != nil {
		t.Fatal(err)
	}
	a, err := Open(dir)
	if err != nil {
		t.Fatalf("retired setting must not stop startup: %v", err)
	}
	defer a.Close()
	if a.settings.Model != "old/model" || a.settings.ClassifyOnImport {
		t.Fatalf("surrounding settings lost: %#v", a.settings)
	}
	if _, err := a.SaveSettings(context.Background(), Settings{Model: "new/model", ClassifyOnImport: true}); err != nil {
		t.Fatal(err)
	}
	written, err := os.ReadFile(path)
	if err != nil {
		t.Fatal(err)
	}
	if strings.Contains(string(written), "include_amount") {
		t.Fatalf("retired setting survived a save: %s", written)
	}
	if err := os.WriteFile(path, []byte("classify_on_imports = true\n"), 0600); err != nil {
		t.Fatal(err)
	}
	if _, err := Open(dir); err == nil {
		t.Fatal("a misspelled setting must still be refused")
	}
}
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")}, nil)
	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)
	}
}

// runPreview drives the background preview job to completion the way the UI
// does: start the run, then poll progress until it reports done.
func runPreview(t *testing.T, a *App, r PreviewRequest) (Preview, error) {
	t.Helper()
	start, err := a.StartPreview(context.Background(), r)
	if err != nil {
		return Preview{}, err
	}
	deadline := time.Now().Add(15 * time.Second)
	for {
		p, err := a.PreviewProgress(start.ID)
		if err != nil {
			return Preview{}, err
		}
		if p.Done {
			if p.Error != "" {
				return Preview{}, errors.New(p.Error)
			}
			return *p.Preview, nil
		}
		if time.Now().After(deadline) {
			t.Fatal("preview run did not finish")
		}
		time.Sleep(5 * time.Millisecond)
	}
}
func TestPreviewCooldownProtectsLaterPreviewsAndImports(t *testing.T) {
	a, s := testApp(t)
	s = seed(t, a, s)
	before := domain.Clone(s.Data)
	var calls atomic.Int32
	provider := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		calls.Add(1)
		w.Header().Set("Retry-After", "300")
		w.WriteHeader(http.StatusTooManyRequests)
	}))
	defer provider.Close()
	a.classifier = classification.Client{APIKey: "test", Model: "test/model", BaseURL: provider.URL}
	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
	defer cancel()

	for _, model := range []string{"test/model", "test/another-model"} {
		preview, err := runPreview(t, a, PreviewRequest{
			Revision: s.Revision, From: "2026-09-01", To: "2026-09-30",
			Model: model, Fields: Fields{Category: true},
		})
		if err != nil {
			t.Fatal(err)
		}
		if preview.Analysed != 2 || len(preview.Errors) != 2 || len(preview.Changes) != 0 {
			t.Fatalf("rate-limited preview did not preserve both records: %+v", preview)
		}
	}
	unchanged, err := a.Snapshot(ctx)
	if err != nil {
		t.Fatal(err)
	}
	if !reflect.DeepEqual(before, unchanged.Data) {
		t.Fatal("rate-limited previews changed canonical data")
	}

	a.mu.Lock()
	result, err := a.importFacts(ctx, unchanged, []domain.Facts{sampleFacts("ALDI", "2026-09-10", "-12.34")}, nil)
	a.mu.Unlock()
	if err != nil {
		t.Fatal(err)
	}
	if result.Imported != 1 || len(result.State.Data.Transactions) != 3 {
		t.Fatal("provider cooldown lost the newly imported record")
	}
	for _, tx := range result.State.Data.Transactions {
		if tx.Facts.ExternalID == hex.EncodeToString([]byte("ALDI")) {
			if tx.Enrichment.Classification.Error == "" || tx.Enrichment.CategoryID != domain.ExpenseFallback {
				t.Fatal("cooldown did not leave imported facts editable and unclassified")
			}
		}
	}
	if got := calls.Load(); got != 1 {
		t.Fatalf("previews and imports bypassed shared provider cooldown: %d requests", got)
	}
}

func TestCancelledPreviewRunProducesNoPreview(t *testing.T) {
	a, s := testApp(t)
	s = seed(t, a, s)
	ids := make(chan string, 1)
	provider := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		// Stop the run from within its first provider call, as the UI's Stop
		// button would mid-request.
		a.CancelPreview(<-ids)
		w.Header().Set("Retry-After", "60")
		w.WriteHeader(http.StatusTooManyRequests)
	}))
	defer provider.Close()
	a.classifier = classification.Client{APIKey: "test", Model: "test/model", BaseURL: provider.URL}
	start, err := a.StartPreview(context.Background(), PreviewRequest{
		Revision: s.Revision, From: "2026-09-09", To: "2026-09-09",
		Model: "test/model", Fields: Fields{Category: true},
	})
	if err != nil {
		t.Fatal(err)
	}
	ids <- start.ID
	deadline := time.Now().Add(10 * time.Second)
	for {
		if _, err := a.PreviewProgress(start.ID); err != nil {
			break // the cancelled run is gone, never a finished preview
		}
		if time.Now().After(deadline) {
			t.Fatal("cancelled preview run still reports progress")
		}
		time.Sleep(5 * time.Millisecond)
	}
	if _, err := a.ApplyPreview(context.Background(), start.ID, s.Revision, []string{"any"}, nil); err == nil {
		t.Fatal("cancelled run produced an applicable preview")
	}
	after, err := a.Snapshot(context.Background())
	if err != nil {
		t.Fatal(err)
	}
	if !reflect.DeepEqual(s.Data, after.Data) {
		t.Fatal("cancelled preview changed canonical data")
	}
}
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 {
			Transactions []struct {
				Ref string `json:"ref"`
			} `json:"transactions"`
			Categories []struct{ ID, Path 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.Path), "groceries") {
				category = c.ID
			}
		}
		answer := map[string]any{"merchant_id": nil, "new_merchant": "REWE", "category_id": category, "tag_ids": []string{}, "confidence": "high"}
		var content []byte
		if len(prompt.Transactions) > 0 {
			items := make([]map[string]any, 0, len(prompt.Transactions))
			for _, row := range prompt.Transactions {
				item := map[string]any{"ref": row.Ref}
				for k, v := range answer {
					item[k] = v
				}
				items = append(items, item)
			}
			content, _ = json.Marshal(map[string]any{"transactions": items})
		} else {
			content, _ = json.Marshal(answer)
		}
		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 := runPreview(t, a, 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}, nil)
	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}, nil); 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 := runPreview(t, a, 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}, nil); 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")
	}
}

// A preview run is minutes long by design (paced provider calls), so a
// scheduled sync, an import, or an earlier partial apply committing in the
// meantime must not invalidate the review: only an edit to a selected
// transaction itself conflicts.
func TestApplyPreviewSurvivesUnrelatedCommitsAndPartialApplies(t *testing.T) {
	ctx := context.Background()
	a, s := testApp(t)
	s = seed(t, a, s)
	mockClassifier(t, a)
	p, err := runPreview(t, a, 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 two proposed changes: %+v", p)
	}
	// An unrelated registry edit moves the journal revision after the preview.
	if _, err = a.Mutate(ctx, s.Revision, func(d *domain.Dataset) error {
		d.Tags = append(d.Tags, domain.Tag{ID: "travel", Name: "travel"})
		return nil
	}); err != nil {
		t.Fatal(err)
	}
	first, err := a.ApplyPreview(ctx, p.ID, p.Revision, []string{p.Changes[0].ID}, nil)
	if err != nil {
		t.Fatalf("unrelated commit invalidated the preview: %v", err)
	}
	// The partial apply moved the revision again; the remaining proposal must
	// still apply without another paced provider run.
	second, err := a.ApplyPreview(ctx, p.ID, p.Revision, []string{p.Changes[1].ID}, nil)
	if err != nil {
		t.Fatalf("partial apply consumed the remaining proposals: %v", err)
	}
	if second.Revision == first.Revision {
		t.Fatal("second apply committed nothing")
	}
	for _, tx := range second.Data.Transactions {
		if tx.Enrichment.CategoryID != "groceries" {
			t.Fatalf("applied categories lost: %+v", tx.Enrichment)
		}
	}
	// Both changes are consumed now; re-applying must fail, not double-write.
	if _, err = a.ApplyPreview(ctx, p.ID, p.Revision, []string{p.Changes[0].ID}, nil); err == nil {
		t.Fatal("consumed change applied twice")
	}
}

// A reviewer can correct a proposal before applying it: the corrected fields
// land instead of the model's, provenance becomes manual, and an invalid or
// unselected correction rejects the whole apply.
func TestApplyPreviewHonoursReviewerEdits(t *testing.T) {
	ctx := context.Background()
	a, s := testApp(t)
	s = seed(t, a, s)
	s, err := a.Mutate(ctx, s.Revision, func(d *domain.Dataset) error {
		d.Categories = append(d.Categories, domain.Category{ID: "dining", Name: "Dining", ParentID: "cat_expenses", Kind: "expense"})
		return nil
	})
	if err != nil {
		t.Fatal(err)
	}
	mockClassifier(t, a)
	p, err := runPreview(t, a, PreviewRequest{Revision: s.Revision, From: "2026-09-01", To: "2026-09-30", Model: "test/model", Fields: Fields{Category: true, Tags: true}})
	if err != nil {
		t.Fatal(err)
	}
	if len(p.Changes) != 2 {
		t.Fatalf("expected two proposed changes: %+v", p)
	}
	edited, other := p.Changes[0], p.Changes[1]
	if _, err = a.ApplyPreview(ctx, p.ID, p.Revision, []string{edited.ID}, []EnrichmentEdit{{ID: edited.ID, CategoryID: "nonexistent", TagIDs: []string{}}}); err == nil {
		t.Fatal("edit naming an unknown category was applied")
	}
	if _, err = a.ApplyPreview(ctx, p.ID, p.Revision, []string{edited.ID}, []EnrichmentEdit{{ID: other.ID, CategoryID: "dining", TagIDs: []string{}}}); err == nil {
		t.Fatal("edit for an unselected transaction was accepted")
	}
	applied, err := a.ApplyPreview(ctx, p.ID, p.Revision, []string{edited.ID, other.ID}, []EnrichmentEdit{{ID: edited.ID, CategoryID: "dining", TagIDs: []string{"home"}}})
	if err != nil {
		t.Fatal(err)
	}
	for _, tx := range applied.Data.Transactions {
		e := tx.Enrichment
		switch tx.Facts.ID {
		case edited.ID:
			if e.CategoryID != "dining" || !reflect.DeepEqual(e.TagIDs, []string{"home"}) {
				t.Fatalf("reviewer correction lost: %+v", e)
			}
			if e.Classification.Source != "manual" {
				t.Fatalf("corrected change kept model provenance: %+v", e.Classification)
			}
		case other.ID:
			if e.CategoryID != "groceries" || e.Classification.Source == "manual" {
				t.Fatalf("uncorrected change altered: %+v", e)
			}
		}
	}
}

// Imports auto-apply only what the model is sure about: a low-confidence
// category lands on the editable fallback while the merchant link and the
// recorded confidence survive for review in Analyse.
func TestImportNeverAutoAppliesLowConfidenceCategory(t *testing.T) {
	a, s := testApp(t)
	provider := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		content := `{"merchant_id":null,"new_merchant":"REWE","category_id":"groceries","tag_ids":[],"confidence":"low"}`
		json.NewEncoder(w).Encode(map[string]any{"choices": []any{map[string]any{
			"finish_reason": "stop",
			"message":       map[string]any{"content": content},
		}}})
	}))
	defer provider.Close()
	a.classifier = classification.Client{APIKey: "test", Model: "test/model", BaseURL: provider.URL}
	s = seed(t, a, s)
	if len(s.Data.Transactions) != 2 {
		t.Fatalf("import lost transactions: %d", len(s.Data.Transactions))
	}
	for _, tx := range s.Data.Transactions {
		e := tx.Enrichment
		if e.CategoryID != domain.ExpenseFallback {
			t.Fatalf("low-confidence category was auto-applied: %+v", e)
		}
		if e.MerchantID == "" || e.Classification.Confidence != "low" || e.Classification.Source != "openrouter" {
			t.Fatalf("merchant link or provenance lost: %+v", e)
		}
	}
}
func TestTaxonomyProposalApprovalMintsOnlyApprovedEntries(t *testing.T) {
	a, s := testApp(t)
	s = seed(t, a, s)
	provider := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		content := `{"categories":[{"name":"Food","parent":"","kind":"expense","hint":"Food purchases","because":["REWE"]},{"name":"Dining","parent":"Food","kind":"expense","hint":"Restaurants","because":["EDEKA"]}],"tags":[{"name":"Recurring","hint":"Repeats regularly"}],"merchants":[{"name":"REWE","aliases":["REWE"]}]}`
		json.NewEncoder(w).Encode(map[string]any{"choices": []any{map[string]any{
			"finish_reason": "stop",
			"message":       map[string]any{"content": content},
		}}})
	}))
	defer provider.Close()
	a.classifier = classification.Client{APIKey: "test", Model: "test/model", BaseURL: provider.URL}
	preview, err := a.ProposeTaxonomy(context.Background(), TaxonomyProposalRequest{
		Revision: s.Revision,
		Model:    "test/model",
	})
	if err != nil {
		t.Fatal(err)
	}
	if len(preview.Sample) != 2 || len(preview.Proposal.Categories) != 2 {
		t.Fatalf("unexpected taxonomy preview: %+v", preview)
	}
	approved := classification.TaxonomyProposal{
		Categories: []classification.ProposedCategory{
			preview.Proposal.Categories[1],
		},
	}
	applied, err := a.ApplyTaxonomy(context.Background(), preview.ID, preview.Revision, approved)
	if err != nil {
		t.Fatal(err)
	}
	foundFood, foundDining := false, false
	for _, category := range applied.Data.Categories {
		foundFood = foundFood || category.Name == "Food"
		foundDining = foundDining || category.Name == "Dining"
	}
	if !foundFood || !foundDining {
		t.Fatalf("approved child did not bring its parent: %+v", applied.Data.Categories)
	}
	if len(applied.Data.Tags) != len(s.Data.Tags) || len(applied.Data.Merchants) != len(s.Data.Merchants) {
		t.Fatal("unapproved taxonomy entries were written")
	}
}