package drift

import (
	"testing"

	"git.agentview.dev/profit/golangLAKEHOUSE/internal/distillation"
)

func mkInput(sourceFile string, persisted distillation.ScoreCategory, succ []string) ScorerDriftInput {
	return ScorerDriftInput{
		Record: distillation.EvidenceRecord{
			RunID:         "run-x",
			TaskID:        "task-x",
			Timestamp:     "2026-01-01T00:00:00Z",
			SchemaVersion: distillation.EvidenceSchemaVersion,
			Provenance: distillation.Provenance{
				SourceFile: sourceFile,
				SigHash:    "abc",
				RecordedAt: "2026-01-01T00:00:01Z",
			},
			SuccessMarkers: succ,
		},
		PersistedCategory: persisted,
	}
}

func TestComputeScorerDrift_NoDrift(t *testing.T) {
	// All inputs have persisted=accepted matching what the current
	// scrum_review scorer produces on accepted_on_attempt_1.
	inputs := []ScorerDriftInput{
		mkInput("data/_kb/scrum_reviews.jsonl", distillation.CategoryAccepted, []string{"accepted_on_attempt_1"}),
		mkInput("data/_kb/scrum_reviews.jsonl", distillation.CategoryAccepted, []string{"accepted_on_attempt_1"}),
		mkInput("data/_kb/scrum_reviews.jsonl", distillation.CategoryAccepted, []string{"accepted_on_attempt_1"}),
	}
	r := ComputeScorerDrift(inputs, true)
	if r.TotalChecked != 3 || r.Matched != 3 || r.Drifted != 0 {
		t.Errorf("no-drift case: total=%d matched=%d drifted=%d",
			r.TotalChecked, r.Matched, r.Drifted)
	}
	if r.DriftRate != 0 {
		t.Errorf("drift_rate: want 0, got %v", r.DriftRate)
	}
	if len(r.Entries) != 0 {
		t.Errorf("entries: want 0, got %d", len(r.Entries))
	}
}

func TestComputeScorerDrift_ShiftDetected(t *testing.T) {
	// Simulate a historical labeling where the persisted scorer
	// thought attempt-2 acceptances were "accepted" but the current
	// scorer (this code) categorizes them as "partially_accepted".
	// Drift should fire on those.
	inputs := []ScorerDriftInput{
		// Match: attempt 1 → accepted (still)
		mkInput("data/_kb/scrum_reviews.jsonl", distillation.CategoryAccepted, []string{"accepted_on_attempt_1"}),
		mkInput("data/_kb/scrum_reviews.jsonl", distillation.CategoryAccepted, []string{"accepted_on_attempt_1"}),
		// Drift: persisted thought attempt-2 was accepted, today's scorer says partial
		mkInput("data/_kb/scrum_reviews.jsonl", distillation.CategoryAccepted, []string{"accepted_on_attempt_2"}),
		mkInput("data/_kb/scrum_reviews.jsonl", distillation.CategoryAccepted, []string{"accepted_on_attempt_3"}),
		// Drift: persisted thought attempt-5 was accepted, today's scorer says partial (high-cost)
		mkInput("data/_kb/scrum_reviews.jsonl", distillation.CategoryAccepted, []string{"accepted_on_attempt_5"}),
	}
	r := ComputeScorerDrift(inputs, true)
	if r.TotalChecked != 5 {
		t.Errorf("total: want 5, got %d", r.TotalChecked)
	}
	if r.Matched != 2 {
		t.Errorf("matched: want 2, got %d", r.Matched)
	}
	if r.Drifted != 3 {
		t.Errorf("drifted: want 3, got %d", r.Drifted)
	}
	wantRate := 3.0 / 5.0
	if r.DriftRate < wantRate-1e-9 || r.DriftRate > wantRate+1e-9 {
		t.Errorf("drift_rate: want %v, got %v", wantRate, r.DriftRate)
	}
	if len(r.Entries) != 3 {
		t.Errorf("entries: want 3 mismatches, got %d", len(r.Entries))
	}
	// Shift matrix should show one shift: accepted → partially_accepted, count=3
	if len(r.ShiftMatrix) != 1 {
		t.Errorf("shift matrix: want 1 shift, got %d (%+v)", len(r.ShiftMatrix), r.ShiftMatrix)
	} else {
		s := r.ShiftMatrix[0]
		if s.From != distillation.CategoryAccepted ||
			s.To != distillation.CategoryPartiallyAccepted ||
			s.Count != 3 {
			t.Errorf("shift: got %+v", s)
		}
	}
}

func TestComputeScorerDrift_MultipleShiftsSortedByCount(t *testing.T) {
	inputs := []ScorerDriftInput{
		// 3× accepted→partial
		mkInput("data/_kb/scrum_reviews.jsonl", distillation.CategoryAccepted, []string{"accepted_on_attempt_2"}),
		mkInput("data/_kb/scrum_reviews.jsonl", distillation.CategoryAccepted, []string{"accepted_on_attempt_2"}),
		mkInput("data/_kb/scrum_reviews.jsonl", distillation.CategoryAccepted, []string{"accepted_on_attempt_2"}),
		// 1× rejected→needs_human (no marker)
		{
			Record: distillation.EvidenceRecord{
				RunID: "r1", TaskID: "t1",
				Timestamp:     "2026-01-01T00:00:00Z",
				SchemaVersion: distillation.EvidenceSchemaVersion,
				Provenance: distillation.Provenance{
					SourceFile: "data/_kb/scrum_reviews.jsonl",
					SigHash:    "x", RecordedAt: "2026-01-01T00:00:01Z",
				},
				// no markers → needs_human_review
			},
			PersistedCategory: distillation.CategoryRejected,
		},
	}
	r := ComputeScorerDrift(inputs, false)
	if r.Drifted != 4 {
		t.Errorf("drifted: want 4, got %d", r.Drifted)
	}
	if len(r.ShiftMatrix) != 2 {
		t.Errorf("shift matrix: want 2 distinct shifts, got %d", len(r.ShiftMatrix))
	}
	// Sorted by count desc, so accepted→partial (3) before rejected→needs_human (1)
	if r.ShiftMatrix[0].Count != 3 || r.ShiftMatrix[1].Count != 1 {
		t.Errorf("shift order wrong: got %+v", r.ShiftMatrix)
	}
}

func TestComputeScorerDrift_IncludeEntriesFalse(t *testing.T) {
	inputs := []ScorerDriftInput{
		mkInput("data/_kb/scrum_reviews.jsonl", distillation.CategoryAccepted, []string{"accepted_on_attempt_2"}),
	}
	r := ComputeScorerDrift(inputs, false)
	if r.Drifted != 1 {
		t.Errorf("drifted: want 1, got %d", r.Drifted)
	}
	if len(r.Entries) != 0 {
		t.Errorf("entries: want 0 when includeEntries=false, got %d", len(r.Entries))
	}
}

func TestComputeScorerDrift_EmptyInput(t *testing.T) {
	r := ComputeScorerDrift(nil, true)
	if r.TotalChecked != 0 || r.Drifted != 0 || r.Matched != 0 {
		t.Errorf("empty: want all-zero, got %+v", r)
	}
	if r.DriftRate != 0 {
		t.Errorf("drift_rate on empty: want 0, got %v", r.DriftRate)
	}
}

func TestComputeScorerDrift_ScorerVersionStamped(t *testing.T) {
	r := ComputeScorerDrift(nil, false)
	if r.ScorerVersion != distillation.ScorerVersion {
		t.Errorf("scorer_version: want %q, got %q", distillation.ScorerVersion, r.ScorerVersion)
	}
}