package services

import (
	"bookhoard/internal/database"
	"encoding/json"
	"testing"

	"github.com/jackc/pgx/v5/pgtype"
	"github.com/stretchr/testify/assert"
	"github.com/stretchr/testify/require"
)

func TestEvaluateRules_Equality(t *testing.T) {
	service := &CollectionService{}

	mediaItem := database.MediaItems{
		Genre: pgtype.Text{String: "Science Fiction", Valid: true},
	}

	rules := []Rule{
		{
			ID:       "rule-1",
			Field:    "genre",
			Operator: "equals",
			Value:    "Science Fiction",
			Priority: 5,
		},
	}

	evaluations := service.EvaluateRules(mediaItem, 0, rules)

	if len(evaluations) != 1 {
		t.Fatalf("expected 1 evaluation, got %d", len(evaluations))
	}

	if !evaluations[0].Matches {
		t.Errorf("expected rule to match, but it didn't")
	}

	if evaluations[0].Confidence <= 0.85 {
		t.Errorf("expected confidence > 0.85, got %f", evaluations[0].Confidence)
	}
}

func TestEvaluateRules_NoMatch(t *testing.T) {
	service := &CollectionService{}

	mediaItem := database.MediaItems{
		Genre: pgtype.Text{String: "Fantasy", Valid: true},
	}

	rules := []Rule{
		{
			ID:       "rule-1",
			Field:    "genre",
			Operator: "equals",
			Value:    "Science Fiction",
			Priority: 5,
		},
	}

	evaluations := service.EvaluateRules(mediaItem, 0, rules)

	if len(evaluations) != 1 {
		t.Fatalf("expected 1 evaluation, got %d", len(evaluations))
	}

	if evaluations[0].Matches {
		t.Errorf("expected rule not to match, but it did")
	}

	if evaluations[0].Confidence != 0 {
		t.Errorf("expected confidence 0, got %f", evaluations[0].Confidence)
	}
}

func TestEvaluateRules_Contains(t *testing.T) {
	service := &CollectionService{}

	mediaItem := database.MediaItems{
		Series: pgtype.Text{String: "The Expanse", Valid: true},
	}

	rules := []Rule{
		{
			ID:       "rule-1",
			Field:    "series",
			Operator: "contains",
			Value:    "Expanse",
			Priority: 7,
		},
	}

	evaluations := service.EvaluateRules(mediaItem, 0, rules)

	if len(evaluations) != 1 {
		t.Fatalf("expected 1 evaluation, got %d", len(evaluations))
	}

	if !evaluations[0].Matches {
		t.Errorf("expected rule to match, but it didn't")
	}

	if evaluations[0].Confidence <= 0.9 {
		t.Errorf("expected confidence > 0.9 with priority boost, got %f", evaluations[0].Confidence)
	}
}

func TestEvaluateRules_PriorityOrder(t *testing.T) {
	service := &CollectionService{}

	mediaItem := database.MediaItems{
		Genre:  pgtype.Text{String: "Science Fiction", Valid: true},
		Series: pgtype.Text{String: "Foundation", Valid: true},
	}

	rules := []Rule{
		{
			ID:       "rule-1",
			Field:    "genre",
			Operator: "equals",
			Value:    "Science Fiction",
			Priority: 5,
		},
		{
			ID:       "rule-2",
			Field:    "series",
			Operator: "equals",
			Value:    "Foundation",
			Priority: 9,
		},
	}

	evaluations := service.EvaluateRules(mediaItem, 0, rules)

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

	if evaluations[0].RuleID != "rule-2" {
		t.Errorf("expected rule-2 (higher priority) to be first, got %s", evaluations[0].RuleID)
	}

	if evaluations[1].RuleID != "rule-1" {
		t.Errorf("expected rule-1 (lower priority) to be second, got %s", evaluations[1].RuleID)
	}

	if evaluations[0].Confidence <= evaluations[1].Confidence {
		t.Errorf("expected higher priority rule to have higher confidence")
	}
}

func TestEvaluateRules_CopyrightYear(t *testing.T) {
	service := &CollectionService{}

	mediaItem := database.MediaItems{
		CopyrightYear: pgtype.Int4{Int32: 2020, Valid: true},
	}

	rules := []Rule{
		{
			ID:       "rule-1",
			Field:    "copyright_year",
			Operator: "greater_than",
			Value:    "2019",
			Priority: 5,
		},
	}

	evaluations := service.EvaluateRules(mediaItem, 0, rules)

	if len(evaluations) != 1 {
		t.Fatalf("expected 1 evaluation, got %d", len(evaluations))
	}

	if !evaluations[0].Matches {
		t.Errorf("expected rule to match (2020 > 2019), but it didn't")
	}
}

func TestEvaluateRules_MissingField(t *testing.T) {
	service := &CollectionService{}

	mediaItem := database.MediaItems{}

	rules := []Rule{
		{
			ID:       "rule-1",
			Field:    "genre",
			Operator: "equals",
			Value:    "Science Fiction",
			Priority: 5,
		},
	}

	evaluations := service.EvaluateRules(mediaItem, 0, rules)

	if len(evaluations) != 1 {
		t.Fatalf("expected 1 evaluation, got %d", len(evaluations))
	}

	if evaluations[0].Matches {
		t.Errorf("expected rule not to match when field is missing, but it did")
	}
}

func TestEvaluateRules_CaseInsensitive(t *testing.T) {
	service := &CollectionService{}

	mediaItem := database.MediaItems{
		Genre: pgtype.Text{String: "science fiction", Valid: true},
	}

	rules := []Rule{
		{
			ID:       "rule-1",
			Field:    "genre",
			Operator: "equals",
			Value:    "SCIENCE FICTION",
			Priority: 5,
		},
	}

	evaluations := service.EvaluateRules(mediaItem, 0, rules)

	if len(evaluations) != 1 {
		t.Fatalf("expected 1 evaluation, got %d", len(evaluations))
	}

	if !evaluations[0].Matches {
		t.Errorf("expected case-insensitive match, but it didn't match")
	}
}

func TestEvaluateRules_PriorityBoost(t *testing.T) {
	service := &CollectionService{}

	mediaItem := database.MediaItems{
		Genre: pgtype.Text{String: "Science Fiction", Valid: true},
	}

	rules := []Rule{
		{
			ID:       "rule-1",
			Field:    "genre",
			Operator: "equals",
			Value:    "Science Fiction",
			Priority: 1,
		},
		{
			ID:       "rule-2",
			Field:    "genre",
			Operator: "equals",
			Value:    "Science Fiction",
			Priority: 10,
		},
	}

	evaluations := service.EvaluateRules(mediaItem, 0, rules)

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

	// Higher priority (10) should give higher confidence than lower priority (1)
	// Genre base confidence is 0.9
	// Priority 1: 0.9 + 0.01 = 0.91
	// Priority 10: 0.9 + 0.1 = 1.0 (capped)
	if evaluations[0].Confidence != 1.0 {
		t.Errorf("expected higher priority confidence to be 1.0, got %f", evaluations[0].Confidence)
	}

	if evaluations[1].Confidence != 0.91 {
		t.Errorf("expected lower priority confidence to be 0.91, got %f", evaluations[1].Confidence)
	}

	// The higher priority rule should come first (sorted by priority descending)
	if evaluations[0].RuleID != "rule-2" {
		t.Errorf("expected higher priority rule to be first, got %s", evaluations[0].RuleID)
	}
}

func TestRulesToFilterTree(t *testing.T) {
	t.Run("episode_rules_map_mechanically", func(t *testing.T) {
		rules := []Rule{
			{ID: "1", Field: "feed", Operator: "in", Value: "feed-a, feed-b"},
			{ID: "2", Field: "played", Operator: "equals", Value: "false"},
			{ID: "3", Field: "downloaded", Operator: "equals", Value: "true"},
			{ID: "4", Field: "published_within", Operator: "greater_than", Value: "7"},
		}
		tree, err := RulesToFilterTree(rules, RuleMatchAll)
		require.NoError(t, err)
		assert.Equal(t, RuleMatchAll, tree.Mode, "the collection's match mode becomes the tree mode")
		assert.Equal(t, ScopeEpisodes, tree.Scope, "episode rules force the episodes scope")
		require.Len(t, tree.Children, 4)
		assert.Equal(t, FilterChild{Field: "feed", Op: OpIn, Values: []string{"feed-a", "feed-b"}}, tree.Children[0])
		assert.Equal(t, FilterChild{Field: "played", Op: OpIsFalse}, tree.Children[1])
		assert.Equal(t, FilterChild{Field: "downloaded", Op: OpIsTrue}, tree.Children[2])
		assert.Equal(t, FilterChild{Field: "published_date", Op: OpWithinDays, Values: []string{"7"}}, tree.Children[3])
		// The converted tree parses under the strict engine.
		b, _ := json.Marshal(tree)
		_, err = ParseFilterTree(string(b))
		require.NoError(t, err, "converted tree must satisfy the engine grammar")
	})

	t.Run("book_rules_map_and_stay_books_scope", func(t *testing.T) {
		rules := []Rule{
			{Field: "genre", Operator: "equals", Value: "fantasy"},
			{Field: "author", Operator: "contains", Value: "Voss"},
			{Field: "copyright_year", Operator: "greater_than", Value: "1990"},
			{Field: "tags", Operator: "starts_with", Value: "dyst"},
		}
		tree, err := RulesToFilterTree(rules, RuleMatchAny)
		require.NoError(t, err)
		assert.Equal(t, "", tree.Scope, "no episode rules → the books scope (legacy default)")
		assert.Equal(t, RuleMatchAny, tree.Mode)
		assert.Equal(t, FilterChild{Field: "genre", Op: OpIs, Values: []string{"fantasy"}}, tree.Children[0])
		assert.Equal(t, FilterChild{Field: "copyright_year", Op: OpAtLeast, Values: []string{"1990"}}, tree.Children[2])
		// Documented fallback: rules ops without an engine equivalent
		// (starts_with/ends_with) become contains.
		assert.Equal(t, OpContains, tree.Children[3].Op)
	})
}