package contracts

import (
	"context"
	"reflect"
	"strings"
	"testing"

	"gitea.maximumdirect.net/eric/audita/internal/core/chunking"
	"gitea.maximumdirect.net/eric/audita/internal/core/schema"
	"gitea.maximumdirect.net/eric/audita/internal/framework/proposals"
)

// testChunkProposalHarness is a test-only helper that composes existing
// deterministic chunking and proposal-application primitives.
// It isolates proposal/composition behavior from full runner orchestration.
type testChunkProposalHarness struct {
	module TranscriptModule
}

func (h testChunkProposalHarness) collectEnrichedProposals(
	ctx context.Context,
	transcript *schema.Transcript,
	sections []chunking.Section,
) ([]proposals.EnrichedCorrectionProposal, error) {
	runSpecs, err := ResolveModuleRunSpecs([]string{h.module.Key()})
	if err != nil {
		return nil, err
	}

	runSpec := runSpecs[0]
	runSpec.ReplacementPolicy = h.module.ReplacementPolicy()

	out := make([]proposals.EnrichedCorrectionProposal, 0)
	nextIndex := 0

	for _, section := range sections {
		sectionMeta := SectionMetadataFromSection(section)
		base, err := h.module.Propose(ctx, ProposalRequest{
			ExecutionContext: ExecutionContext{
				WorkingTranscript: transcript,
				Section:           &sectionMeta,
			},
			RunSpec: runSpec,
		})
		if err != nil {
			return nil, err
		}

		for _, proposal := range base {
			sectionIndex := section.Index
			out = append(out, proposals.EnrichedCorrectionProposal{
				CorrectionProposal: proposal,
				ProposalMetadata: proposals.ProposalMetadata{
					ProposalIndex:  nextIndex,
					ModuleKey:      runSpec.ModuleKey,
					ModuleInstance: runSpec.InstanceName,
					SectionIndex:   &sectionIndex,
				},
			})
			nextIndex++
		}
	}

	return out, nil
}

type deterministicReplacementRule struct {
	OriginalText  string
	CorrectedText string
	Confidence    float64
}

type deterministicFakeModule struct {
	key               string
	replacementPolicy proposals.ReplacementPolicy
	rules             []deterministicReplacementRule
}

func (m deterministicFakeModule) Key() string { return m.key }

func (m deterministicFakeModule) ReplacementPolicy() proposals.ReplacementPolicy {
	return m.replacementPolicy
}

func (m deterministicFakeModule) Validators() []Validator { return nil }

func (m deterministicFakeModule) Propose(ctx context.Context, req ProposalRequest) ([]proposals.CorrectionProposal, error) {
	_ = ctx

	if req.WorkingTranscript == nil || req.Section == nil {
		return []proposals.CorrectionProposal{}, nil
	}

	out := make([]proposals.CorrectionProposal, 0)
	for _, seg := range req.WorkingTranscript.Segments {
		if seg.ID < req.Section.StartSegmentID || seg.ID > req.Section.EndSegmentID {
			continue
		}

		for _, rule := range m.rules {
			if strings.Contains(seg.Text, rule.OriginalText) {
				out = append(out, proposals.CorrectionProposal{
					TargetSegmentID: seg.ID,
					OriginalText:    rule.OriginalText,
					CorrectedText:   rule.CorrectedText,
					Confidence:      rule.Confidence,
				})
			}
		}
	}

	return out, nil
}

func TestChunkProposalMetadataAssociation(t *testing.T) {
	transcript := integrationTranscriptFixture()
	sections := mustChunkFixtureTranscript(t, transcript)

	module := deterministicFakeModule{
		key:               "fake_rewriter",
		replacementPolicy: proposals.ReplacementPolicyRequireUnique,
		rules: []deterministicReplacementRule{
			{OriginalText: "alpha", CorrectedText: "ALPHA", Confidence: 0.9},
			{OriginalText: "charlie", CorrectedText: "CHARLIE", Confidence: 0.9},
		},
	}

	harness := testChunkProposalHarness{module: module}
	enriched, err := harness.collectEnrichedProposals(context.Background(), transcript, sections)
	if err != nil {
		t.Fatalf("collectEnrichedProposals failed: %v", err)
	}

	if len(sections) != 2 {
		t.Fatalf("expected 2 sections, got %d", len(sections))
	}
	if len(enriched) != 2 {
		t.Fatalf("expected 2 enriched proposals, got %d", len(enriched))
	}

	if enriched[0].SectionIndex == nil || *enriched[0].SectionIndex != 0 {
		t.Fatalf("expected first proposal section_index=0, got %v", enriched[0].SectionIndex)
	}
	if enriched[1].SectionIndex == nil || *enriched[1].SectionIndex != 1 {
		t.Fatalf("expected second proposal section_index=1, got %v", enriched[1].SectionIndex)
	}
}

func TestDeterministicProposalIndexAssignment(t *testing.T) {
	transcript := integrationTranscriptFixture()
	sections := mustChunkFixtureTranscript(t, transcript)
	module := deterministicFakeModule{
		key:               "fake_rewriter",
		replacementPolicy: proposals.ReplacementPolicyRequireUnique,
		rules: []deterministicReplacementRule{
			{OriginalText: "alpha", CorrectedText: "ALPHA", Confidence: 0.9},
			{OriginalText: "alpha one", CorrectedText: "ALPHA-ONE", Confidence: 0.9},
			{OriginalText: "charlie", CorrectedText: "CHARLIE", Confidence: 0.9},
		},
	}

	harness := testChunkProposalHarness{module: module}
	first, err := harness.collectEnrichedProposals(context.Background(), transcript, sections)
	if err != nil {
		t.Fatalf("first collect failed: %v", err)
	}
	second, err := harness.collectEnrichedProposals(context.Background(), transcript, sections)
	if err != nil {
		t.Fatalf("second collect failed: %v", err)
	}

	if len(first) != len(second) {
		t.Fatalf("proposal length mismatch: %d vs %d", len(first), len(second))
	}

	for i := range first {
		if first[i].ProposalIndex != i {
			t.Fatalf("expected first pass proposal index %d at slot %d, got %d", i, i, first[i].ProposalIndex)
		}
		if second[i].ProposalIndex != i {
			t.Fatalf("expected second pass proposal index %d at slot %d, got %d", i, i, second[i].ProposalIndex)
		}
		if first[i].TargetSegmentID != second[i].TargetSegmentID ||
			first[i].OriginalText != second[i].OriginalText ||
			first[i].CorrectedText != second[i].CorrectedText {
			t.Fatalf("proposal mismatch at index %d", i)
		}
	}
}

func TestApplyFakeProposalsAcrossMultipleChunksWithStaleSkip(t *testing.T) {
	transcript := integrationTranscriptFixture()
	sections := mustChunkFixtureTranscript(t, transcript)

	module := deterministicFakeModule{
		key:               "fake_rewriter",
		replacementPolicy: proposals.ReplacementPolicyRequireUnique,
		rules: []deterministicReplacementRule{
			{OriginalText: "alpha", CorrectedText: "ALPHA", Confidence: 0.9},
			{OriginalText: "alpha one", CorrectedText: "ALPHA-ONE", Confidence: 0.9},
			{OriginalText: "charlie", CorrectedText: "CHARLIE", Confidence: 0.9},
		},
	}

	harness := testChunkProposalHarness{module: module}
	enriched, err := harness.collectEnrichedProposals(context.Background(), transcript, sections)
	if err != nil {
		t.Fatalf("collectEnrichedProposals failed: %v", err)
	}

	result := proposals.ApplyProposals(transcript, enriched, module.ReplacementPolicy())

	if len(result.Applied) != 2 {
		t.Fatalf("expected 2 applied changes, got %d", len(result.Applied))
	}
	if len(result.Skipped) != 1 {
		t.Fatalf("expected 1 skipped change, got %d", len(result.Skipped))
	}
	if result.Skipped[0].SkipReason != proposals.SkipReasonMissingOriginalText {
		t.Fatalf("expected stale skip reason %q, got %q", proposals.SkipReasonMissingOriginalText, result.Skipped[0].SkipReason)
	}

	if got := result.Transcript.Segments[0].Text; got != "ALPHA one" {
		t.Fatalf("unexpected segment 1 text: %q", got)
	}
	if got := result.Transcript.Segments[2].Text; got != "CHARLIE three" {
		t.Fatalf("unexpected segment 3 text: %q", got)
	}
}

func TestChunkProposalCompositionDoesNotMutateNormalizedTranscript(t *testing.T) {
	transcript := integrationTranscriptFixture()
	before := cloneTranscriptForComparison(transcript)
	sections := mustChunkFixtureTranscript(t, transcript)

	module := deterministicFakeModule{
		key:               "fake_rewriter",
		replacementPolicy: proposals.ReplacementPolicyRequireUnique,
		rules: []deterministicReplacementRule{
			{OriginalText: "alpha", CorrectedText: "ALPHA", Confidence: 0.9},
			{OriginalText: "charlie", CorrectedText: "CHARLIE", Confidence: 0.9},
		},
	}

	harness := testChunkProposalHarness{module: module}
	enriched, err := harness.collectEnrichedProposals(context.Background(), transcript, sections)
	if err != nil {
		t.Fatalf("collectEnrichedProposals failed: %v", err)
	}

	_ = proposals.ApplyProposals(transcript, enriched, module.ReplacementPolicy())

	if !reflect.DeepEqual(transcript, before) {
		t.Fatalf("normalized transcript mutated\nbefore=%+v\nafter=%+v", before, transcript)
	}
}

func integrationTranscriptFixture() *schema.Transcript {
	return &schema.Transcript{
		Segments: []schema.Segment{
			{ID: 1, Speaker: "A", Start: 0, End: 1, Text: "alpha one"},
			{ID: 2, Speaker: "A", Start: 1, End: 2, Text: "bravo two"},
			{ID: 3, Speaker: "B", Start: 2, End: 3, Text: "charlie three"},
			{ID: 4, Speaker: "B", Start: 3, End: 4, Text: "delta four"},
		},
	}
}

func mustChunkFixtureTranscript(t *testing.T, transcript *schema.Transcript) []chunking.Section {
	t.Helper()
	chunker := chunking.NewChunkerWithEstimator(
		chunking.ChunkingConfig{MaxSectionTokens: 2, MinSectionTokens: 0},
		&chunking.ConstTokenEstimator{Tokens: 1},
	)

	sections, err := chunker.ChunkTranscript(transcript)
	if err != nil {
		t.Fatalf("chunk transcript failed: %v", err)
	}

	if len(sections) != 2 {
		t.Fatalf("expected fixture chunking to produce 2 sections, got %d", len(sections))
	}

	return sections
}

func cloneTranscriptForComparison(in *schema.Transcript) *schema.Transcript {
	if in == nil {
		return nil
	}

	out := &schema.Transcript{Segments: make([]schema.Segment, len(in.Segments))}
	for i, seg := range in.Segments {
		cloned := seg
		if seg.Categories != nil {
			cloned.Categories = append([]string(nil), seg.Categories...)
		}
		out.Segments[i] = cloned
	}

	return out
}