package store

import (
	"context"
	"encoding/json"
	"fmt"
	"sort"
	"strings"
	"time"

	"github.com/google/uuid"
	"github.com/jackc/pgx/v5"
	"github.com/pgvector/pgvector-go"

	thoughttypes "git.warky.dev/wdevs/amcs/internal/types"
)

func (db *DB) InsertThought(ctx context.Context, thought thoughttypes.Thought, embeddingModel string) (thoughttypes.Thought, error) {
	metadata, err := json.Marshal(thought.Metadata)
	if err != nil {
		return thoughttypes.Thought{}, fmt.Errorf("marshal metadata: %w", err)
	}

	tx, err := db.pool.Begin(ctx)
	if err != nil {
		return thoughttypes.Thought{}, fmt.Errorf("begin transaction: %w", err)
	}
	defer func() {
		_ = tx.Rollback(ctx)
	}()

	row := tx.QueryRow(ctx, `
		insert into thoughts (content, metadata, project_id)
		values ($1, $2::jsonb, $3)
		returning guid, created_at, updated_at
	`, thought.Content, metadata, thought.ProjectID)

	created := thought
	created.Embedding = nil
	if err := row.Scan(&created.ID, &created.CreatedAt, &created.UpdatedAt); err != nil {
		return thoughttypes.Thought{}, fmt.Errorf("insert thought: %w", err)
	}

	if len(thought.Embedding) > 0 && embeddingModel != "" {
		if _, err := tx.Exec(ctx, `
			insert into embeddings (thought_id, model, dim, embedding)
			values ($1, $2, $3, $4)
			on conflict (thought_id, model) do update
				set embedding = excluded.embedding,
				    dim = excluded.dim,
				    updated_at = now()
		`, created.ID, embeddingModel, len(thought.Embedding), pgvector.NewVector(thought.Embedding)); err != nil {
			return thoughttypes.Thought{}, fmt.Errorf("insert embedding: %w", err)
		}
	}

	if err := tx.Commit(ctx); err != nil {
		return thoughttypes.Thought{}, fmt.Errorf("commit thought insert: %w", err)
	}

	return created, nil
}

func (db *DB) SearchThoughts(ctx context.Context, embedding []float32, embeddingModel string, threshold float64, limit int, filter map[string]any) ([]thoughttypes.SearchResult, error) {
	filterJSON, err := json.Marshal(filter)
	if err != nil {
		return nil, fmt.Errorf("marshal search filter: %w", err)
	}

	rows, err := db.pool.Query(ctx, `
		select id, content, metadata, similarity, created_at
		from match_thoughts($1, $2, $3, $4::jsonb, $5)
	`, pgvector.NewVector(embedding), threshold, limit, filterJSON, embeddingModel)
	if err != nil {
		return nil, fmt.Errorf("search thoughts: %w", err)
	}
	defer rows.Close()

	results := make([]thoughttypes.SearchResult, 0, limit)
	for rows.Next() {
		var result thoughttypes.SearchResult
		var metadataBytes []byte
		if err := rows.Scan(&result.ID, &result.Content, &metadataBytes, &result.Similarity, &result.CreatedAt); err != nil {
			return nil, fmt.Errorf("scan search result: %w", err)
		}
		if err := json.Unmarshal(metadataBytes, &result.Metadata); err != nil {
			return nil, fmt.Errorf("decode search metadata: %w", err)
		}
		results = append(results, result)
	}

	if err := rows.Err(); err != nil {
		return nil, fmt.Errorf("iterate search results: %w", err)
	}

	return results, nil
}

func (db *DB) ListThoughts(ctx context.Context, filter thoughttypes.ListFilter) ([]thoughttypes.Thought, error) {
	args := make([]any, 0, 6)
	conditions := []string{}

	if !filter.IncludeArchived {
		conditions = append(conditions, "archived_at is null")
	}
	if value := strings.TrimSpace(filter.Type); value != "" {
		args = append(args, value)
		conditions = append(conditions, fmt.Sprintf("metadata->>'type' = $%d", len(args)))
	}
	if value := strings.TrimSpace(filter.Topic); value != "" {
		args = append(args, value)
		conditions = append(conditions, fmt.Sprintf("metadata->'topics' ? $%d", len(args)))
	}
	if value := strings.TrimSpace(filter.Person); value != "" {
		args = append(args, value)
		conditions = append(conditions, fmt.Sprintf("metadata->'people' ? $%d", len(args)))
	}
	if filter.Days > 0 {
		args = append(args, time.Now().Add(-time.Duration(filter.Days)*24*time.Hour))
		conditions = append(conditions, fmt.Sprintf("created_at >= $%d", len(args)))
	}
	if filter.ProjectID != nil {
		args = append(args, *filter.ProjectID)
		conditions = append(conditions, fmt.Sprintf("project_id = $%d", len(args)))
	}

	query := `
		select guid, content, metadata, project_id, archived_at, created_at, updated_at
		from thoughts
	`
	if len(conditions) > 0 {
		query += " where " + strings.Join(conditions, " and ")
	}

	args = append(args, filter.Limit)
	query += fmt.Sprintf(" order by created_at desc limit $%d", len(args))

	rows, err := db.pool.Query(ctx, query, args...)
	if err != nil {
		return nil, fmt.Errorf("list thoughts: %w", err)
	}
	defer rows.Close()

	thoughts := make([]thoughttypes.Thought, 0, filter.Limit)
	for rows.Next() {
		var thought thoughttypes.Thought
		var metadataBytes []byte
		if err := rows.Scan(&thought.ID, &thought.Content, &metadataBytes, &thought.ProjectID, &thought.ArchivedAt, &thought.CreatedAt, &thought.UpdatedAt); err != nil {
			return nil, fmt.Errorf("scan listed thought: %w", err)
		}
		if err := json.Unmarshal(metadataBytes, &thought.Metadata); err != nil {
			return nil, fmt.Errorf("decode listed metadata: %w", err)
		}
		thoughts = append(thoughts, thought)
	}

	if err := rows.Err(); err != nil {
		return nil, fmt.Errorf("iterate listed thoughts: %w", err)
	}

	return thoughts, nil
}

func (db *DB) Stats(ctx context.Context) (thoughttypes.ThoughtStats, error) {
	var total int
	if err := db.pool.QueryRow(ctx, `select count(*) from thoughts where archived_at is null`).Scan(&total); err != nil {
		return thoughttypes.ThoughtStats{}, fmt.Errorf("count thoughts: %w", err)
	}

	rows, err := db.pool.Query(ctx, `select metadata from thoughts where archived_at is null`)
	if err != nil {
		return thoughttypes.ThoughtStats{}, fmt.Errorf("query stats metadata: %w", err)
	}
	defer rows.Close()

	stats := thoughttypes.ThoughtStats{
		TotalCount: total,
		TypeCounts: map[string]int{},
	}
	topics := map[string]int{}
	people := map[string]int{}

	for rows.Next() {
		var metadataBytes []byte
		if err := rows.Scan(&metadataBytes); err != nil {
			return thoughttypes.ThoughtStats{}, fmt.Errorf("scan stats metadata: %w", err)
		}

		var metadata thoughttypes.ThoughtMetadata
		if err := json.Unmarshal(metadataBytes, &metadata); err != nil {
			return thoughttypes.ThoughtStats{}, fmt.Errorf("decode stats metadata: %w", err)
		}

		stats.TypeCounts[metadata.Type]++
		for _, topic := range metadata.Topics {
			topics[topic]++
		}
		for _, person := range metadata.People {
			people[person]++
		}
	}

	if err := rows.Err(); err != nil {
		return thoughttypes.ThoughtStats{}, fmt.Errorf("iterate stats metadata: %w", err)
	}

	stats.TopTopics = topCounts(topics, 10)
	stats.TopPeople = topCounts(people, 10)
	return stats, nil
}

func (db *DB) GetThought(ctx context.Context, id uuid.UUID) (thoughttypes.Thought, error) {
	row := db.pool.QueryRow(ctx, `
		select guid, content, metadata, project_id, archived_at, created_at, updated_at
		from thoughts
		where guid = $1
	`, id)

	var thought thoughttypes.Thought
	var metadataBytes []byte
	if err := row.Scan(&thought.ID, &thought.Content, &metadataBytes, &thought.ProjectID, &thought.ArchivedAt, &thought.CreatedAt, &thought.UpdatedAt); err != nil {
		if err == pgx.ErrNoRows {
			return thoughttypes.Thought{}, err
		}
		return thoughttypes.Thought{}, fmt.Errorf("get thought: %w", err)
	}

	if err := json.Unmarshal(metadataBytes, &thought.Metadata); err != nil {
		return thoughttypes.Thought{}, fmt.Errorf("decode thought metadata: %w", err)
	}

	return thought, nil
}

func (db *DB) UpdateThought(ctx context.Context, id uuid.UUID, content string, embedding []float32, embeddingModel string, metadata thoughttypes.ThoughtMetadata, projectID *uuid.UUID) (thoughttypes.Thought, error) {
	metadataBytes, err := json.Marshal(metadata)
	if err != nil {
		return thoughttypes.Thought{}, fmt.Errorf("marshal updated metadata: %w", err)
	}

	tx, err := db.pool.Begin(ctx)
	if err != nil {
		return thoughttypes.Thought{}, fmt.Errorf("begin transaction: %w", err)
	}
	defer func() {
		_ = tx.Rollback(ctx)
	}()

	tag, err := tx.Exec(ctx, `
		update thoughts
		set content    = $2,
		    metadata   = $3::jsonb,
		    project_id = $4,
		    updated_at = now()
		where guid = $1
	`, id, content, metadataBytes, projectID)
	if err != nil {
		return thoughttypes.Thought{}, fmt.Errorf("update thought: %w", err)
	}
	if tag.RowsAffected() == 0 {
		return thoughttypes.Thought{}, pgx.ErrNoRows
	}

	if len(embedding) > 0 && embeddingModel != "" {
		if _, err := tx.Exec(ctx, `
			insert into embeddings (thought_id, model, dim, embedding)
			values ($1, $2, $3, $4)
			on conflict (thought_id, model) do update
				set embedding = excluded.embedding,
				    dim = excluded.dim,
				    updated_at = now()
		`, id, embeddingModel, len(embedding), pgvector.NewVector(embedding)); err != nil {
			return thoughttypes.Thought{}, fmt.Errorf("upsert embedding: %w", err)
		}
	}

	if err := tx.Commit(ctx); err != nil {
		return thoughttypes.Thought{}, fmt.Errorf("commit thought update: %w", err)
	}

	return db.GetThought(ctx, id)
}

func (db *DB) UpdateThoughtMetadata(ctx context.Context, id uuid.UUID, metadata thoughttypes.ThoughtMetadata) (thoughttypes.Thought, error) {
	metadataBytes, err := json.Marshal(metadata)
	if err != nil {
		return thoughttypes.Thought{}, fmt.Errorf("marshal updated metadata: %w", err)
	}

	tag, err := db.pool.Exec(ctx, `
		update thoughts
		set metadata = $2::jsonb,
		    updated_at = now()
		where guid = $1
	`, id, metadataBytes)
	if err != nil {
		return thoughttypes.Thought{}, fmt.Errorf("update thought metadata: %w", err)
	}
	if tag.RowsAffected() == 0 {
		return thoughttypes.Thought{}, pgx.ErrNoRows
	}

	return db.GetThought(ctx, id)
}

func (db *DB) DeleteThought(ctx context.Context, id uuid.UUID) error {
	tag, err := db.pool.Exec(ctx, `delete from thoughts where guid = $1`, id)
	if err != nil {
		return fmt.Errorf("delete thought: %w", err)
	}
	if tag.RowsAffected() == 0 {
		return pgx.ErrNoRows
	}
	return nil
}

func (db *DB) ArchiveThought(ctx context.Context, id uuid.UUID) error {
	tag, err := db.pool.Exec(ctx, `update thoughts set archived_at = now(), updated_at = now() where guid = $1`, id)
	if err != nil {
		return fmt.Errorf("archive thought: %w", err)
	}
	if tag.RowsAffected() == 0 {
		return pgx.ErrNoRows
	}
	return nil
}

func (db *DB) RecentThoughts(ctx context.Context, projectID *uuid.UUID, limit int, days int) ([]thoughttypes.Thought, error) {
	filter := thoughttypes.ListFilter{
		Limit:           limit,
		ProjectID:       projectID,
		Days:            days,
		IncludeArchived: false,
	}
	return db.ListThoughts(ctx, filter)
}

func (db *DB) ListThoughtsPendingMetadataRetry(ctx context.Context, limit int, projectID *uuid.UUID, includeArchived bool, olderThanDays int) ([]thoughttypes.Thought, error) {
	args := make([]any, 0, 4)
	conditions := []string{
		"(metadata->>'metadata_status' = 'pending' or metadata->>'metadata_status' = 'failed')",
	}

	if !includeArchived {
		conditions = append(conditions, "archived_at is null")
	}
	if projectID != nil {
		args = append(args, *projectID)
		conditions = append(conditions, fmt.Sprintf("project_id = $%d", len(args)))
	}
	if olderThanDays > 0 {
		args = append(args, olderThanDays)
		conditions = append(conditions, fmt.Sprintf("coalesce(nullif(metadata->>'metadata_last_attempted_at', '')::timestamptz, created_at) <= now() - ($%d * interval '1 day')", len(args)))
	}

	query := `
		select guid, content, metadata, project_id, archived_at, created_at, updated_at
		from thoughts
		where ` + strings.Join(conditions, " and ")

	args = append(args, limit)
	query += fmt.Sprintf(" order by coalesce(nullif(metadata->>'metadata_last_attempted_at', '')::timestamptz, created_at) asc limit $%d", len(args))

	rows, err := db.pool.Query(ctx, query, args...)
	if err != nil {
		return nil, fmt.Errorf("list thoughts pending metadata retry: %w", err)
	}
	defer rows.Close()

	thoughts := make([]thoughttypes.Thought, 0, limit)
	for rows.Next() {
		var thought thoughttypes.Thought
		var metadataBytes []byte
		if err := rows.Scan(&thought.ID, &thought.Content, &metadataBytes, &thought.ProjectID, &thought.ArchivedAt, &thought.CreatedAt, &thought.UpdatedAt); err != nil {
			return nil, fmt.Errorf("scan pending metadata retry thought: %w", err)
		}
		if err := json.Unmarshal(metadataBytes, &thought.Metadata); err != nil {
			return nil, fmt.Errorf("decode pending metadata retry thought: %w", err)
		}
		thoughts = append(thoughts, thought)
	}

	if err := rows.Err(); err != nil {
		return nil, fmt.Errorf("iterate pending metadata retry thoughts: %w", err)
	}

	return thoughts, nil
}

func (db *DB) SearchSimilarThoughts(ctx context.Context, embedding []float32, embeddingModel string, threshold float64, limit int, projectID *uuid.UUID, excludeID *uuid.UUID) ([]thoughttypes.SearchResult, error) {
	args := []any{pgvector.NewVector(embedding), threshold, embeddingModel}
	conditions := []string{
		"t.archived_at is null",
		"1 - (e.embedding <=> $1) > $2",
		"e.model = $3",
	}
	if projectID != nil {
		args = append(args, *projectID)
		conditions = append(conditions, fmt.Sprintf("t.project_id = $%d", len(args)))
	}
	if excludeID != nil {
		args = append(args, *excludeID)
		conditions = append(conditions, fmt.Sprintf("t.guid <> $%d", len(args)))
	}
	args = append(args, limit)

	query := `
		select t.guid, t.content, t.metadata, 1 - (e.embedding <=> $1) as similarity, t.created_at
		from thoughts t
		join embeddings e on e.thought_id = t.guid
		where ` + strings.Join(conditions, " and ") + fmt.Sprintf(`
		order by e.embedding <=> $1
		limit $%d`, len(args))

	rows, err := db.pool.Query(ctx, query, args...)
	if err != nil {
		return nil, fmt.Errorf("search similar thoughts: %w", err)
	}
	defer rows.Close()

	results := make([]thoughttypes.SearchResult, 0, limit)
	for rows.Next() {
		var result thoughttypes.SearchResult
		var metadataBytes []byte
		if err := rows.Scan(&result.ID, &result.Content, &metadataBytes, &result.Similarity, &result.CreatedAt); err != nil {
			return nil, fmt.Errorf("scan similar thought: %w", err)
		}
		if err := json.Unmarshal(metadataBytes, &result.Metadata); err != nil {
			return nil, fmt.Errorf("decode similar thought metadata: %w", err)
		}
		results = append(results, result)
	}
	if err := rows.Err(); err != nil {
		return nil, fmt.Errorf("iterate similar thoughts: %w", err)
	}
	return results, nil
}

func (db *DB) HasEmbeddingsForModel(ctx context.Context, model string, projectID *uuid.UUID) (bool, error) {
	args := []any{model}
	conditions := []string{
		"e.model = $1",
		"t.archived_at is null",
	}
	if projectID != nil {
		args = append(args, *projectID)
		conditions = append(conditions, fmt.Sprintf("t.project_id = $%d", len(args)))
	}

	query := `select exists(select 1 from embeddings e join thoughts t on t.guid = e.thought_id where ` +
		strings.Join(conditions, " and ") + `)`

	var exists bool
	if err := db.pool.QueryRow(ctx, query, args...).Scan(&exists); err != nil {
		return false, fmt.Errorf("check embeddings for model: %w", err)
	}
	return exists, nil
}

func (db *DB) ListThoughtsMissingEmbedding(ctx context.Context, model string, limit int, projectID *uuid.UUID, includeArchived bool, olderThanDays int) ([]thoughttypes.Thought, error) {
	args := []any{model}
	conditions := []string{"e.id is null"}

	if !includeArchived {
		conditions = append(conditions, "t.archived_at is null")
	}
	if projectID != nil {
		args = append(args, *projectID)
		conditions = append(conditions, fmt.Sprintf("t.project_id = $%d", len(args)))
	}
	if olderThanDays > 0 {
		args = append(args, time.Now().Add(-time.Duration(olderThanDays)*24*time.Hour))
		conditions = append(conditions, fmt.Sprintf("t.created_at < $%d", len(args)))
	}
	args = append(args, limit)

	query := `
		select t.guid, t.content, t.metadata, t.project_id, t.archived_at, t.created_at, t.updated_at
		from thoughts t
		left join embeddings e on e.thought_id = t.guid and e.model = $1
		where ` + strings.Join(conditions, " and ") + `
		order by t.created_at asc
		limit $` + fmt.Sprintf("%d", len(args))

	rows, err := db.pool.Query(ctx, query, args...)
	if err != nil {
		return nil, fmt.Errorf("list thoughts missing embedding: %w", err)
	}
	defer rows.Close()

	thoughts := make([]thoughttypes.Thought, 0, limit)
	for rows.Next() {
		var thought thoughttypes.Thought
		var metadataBytes []byte
		if err := rows.Scan(&thought.ID, &thought.Content, &metadataBytes, &thought.ProjectID, &thought.ArchivedAt, &thought.CreatedAt, &thought.UpdatedAt); err != nil {
			return nil, fmt.Errorf("scan missing-embedding thought: %w", err)
		}
		if err := json.Unmarshal(metadataBytes, &thought.Metadata); err != nil {
			return nil, fmt.Errorf("decode missing-embedding metadata: %w", err)
		}
		thoughts = append(thoughts, thought)
	}
	if err := rows.Err(); err != nil {
		return nil, fmt.Errorf("iterate missing-embedding thoughts: %w", err)
	}
	return thoughts, nil
}

func (db *DB) ListThoughtsForMetadataReparse(ctx context.Context, limit int, projectID *uuid.UUID, includeArchived bool, olderThanDays int) ([]thoughttypes.Thought, error) {
	args := make([]any, 0, 3)
	conditions := make([]string, 0, 4)

	if !includeArchived {
		conditions = append(conditions, "archived_at is null")
	}
	if projectID != nil {
		args = append(args, *projectID)
		conditions = append(conditions, fmt.Sprintf("project_id = $%d", len(args)))
	}
	if olderThanDays > 0 {
		args = append(args, time.Now().Add(-time.Duration(olderThanDays)*24*time.Hour))
		conditions = append(conditions, fmt.Sprintf("created_at < $%d", len(args)))
	}
	args = append(args, limit)

	query := `
		select guid, content, metadata, project_id, archived_at, created_at, updated_at
		from thoughts
	`
	if len(conditions) > 0 {
		query += " where " + strings.Join(conditions, " and ")
	}
	query += " order by created_at asc limit $" + fmt.Sprintf("%d", len(args))

	rows, err := db.pool.Query(ctx, query, args...)
	if err != nil {
		return nil, fmt.Errorf("list thoughts for metadata reparse: %w", err)
	}
	defer rows.Close()

	thoughts := make([]thoughttypes.Thought, 0, limit)
	for rows.Next() {
		var thought thoughttypes.Thought
		var metadataBytes []byte
		if err := rows.Scan(&thought.ID, &thought.Content, &metadataBytes, &thought.ProjectID, &thought.ArchivedAt, &thought.CreatedAt, &thought.UpdatedAt); err != nil {
			return nil, fmt.Errorf("scan metadata-reparse thought: %w", err)
		}
		if err := json.Unmarshal(metadataBytes, &thought.Metadata); err != nil {
			return nil, fmt.Errorf("decode metadata-reparse thought metadata: %w", err)
		}
		thoughts = append(thoughts, thought)
	}
	if err := rows.Err(); err != nil {
		return nil, fmt.Errorf("iterate metadata-reparse thoughts: %w", err)
	}

	return thoughts, nil
}

func (db *DB) UpsertEmbedding(ctx context.Context, thoughtID uuid.UUID, model string, embedding []float32) error {
	_, err := db.pool.Exec(ctx, `
		insert into embeddings (thought_id, model, dim, embedding)
		values ($1, $2, $3, $4)
		on conflict (thought_id, model) do update
			set embedding = excluded.embedding,
			    dim = excluded.dim,
			    updated_at = now()
	`, thoughtID, model, len(embedding), pgvector.NewVector(embedding))
	if err != nil {
		return fmt.Errorf("upsert embedding: %w", err)
	}
	return nil
}

func (db *DB) SearchThoughtsText(ctx context.Context, query string, limit int, projectID *uuid.UUID, excludeID *uuid.UUID) ([]thoughttypes.SearchResult, error) {
	args := []any{query}
	conditions := []string{
		"t.archived_at is null",
		"to_tsvector('simple', t.content) @@ websearch_to_tsquery('simple', $1)",
	}
	if projectID != nil {
		args = append(args, *projectID)
		conditions = append(conditions, fmt.Sprintf("t.project_id = $%d", len(args)))
	}
	if excludeID != nil {
		args = append(args, *excludeID)
		conditions = append(conditions, fmt.Sprintf("t.guid <> $%d", len(args)))
	}
	args = append(args, limit)

	q := `
		select t.guid, t.content, t.metadata,
		       ts_rank_cd(to_tsvector('simple', t.content), websearch_to_tsquery('simple', $1)) as similarity,
		       t.created_at
		from thoughts t
		where ` + strings.Join(conditions, " and ") + `
		order by similarity desc
		limit $` + fmt.Sprintf("%d", len(args))

	rows, err := db.pool.Query(ctx, q, args...)
	if err != nil {
		return nil, fmt.Errorf("text search thoughts: %w", err)
	}
	defer rows.Close()

	results := make([]thoughttypes.SearchResult, 0, limit)
	for rows.Next() {
		var result thoughttypes.SearchResult
		var metadataBytes []byte
		if err := rows.Scan(&result.ID, &result.Content, &metadataBytes, &result.Similarity, &result.CreatedAt); err != nil {
			return nil, fmt.Errorf("scan text search result: %w", err)
		}
		if err := json.Unmarshal(metadataBytes, &result.Metadata); err != nil {
			return nil, fmt.Errorf("decode text search metadata: %w", err)
		}
		results = append(results, result)
	}
	if err := rows.Err(); err != nil {
		return nil, fmt.Errorf("iterate text search results: %w", err)
	}
	return results, nil
}

func topCounts(in map[string]int, limit int) []thoughttypes.KeyCount {
	type kv struct {
		key   string
		count int
	}

	pairs := make([]kv, 0, len(in))
	for key, count := range in {
		if strings.TrimSpace(key) == "" {
			continue
		}
		pairs = append(pairs, kv{key: key, count: count})
	}

	sort.Slice(pairs, func(i, j int) bool {
		if pairs[i].count == pairs[j].count {
			return pairs[i].key < pairs[j].key
		}
		return pairs[i].count > pairs[j].count
	})

	if limit > 0 && len(pairs) > limit {
		pairs = pairs[:limit]
	}

	out := make([]thoughttypes.KeyCount, 0, len(pairs))
	for _, pair := range pairs {
		out = append(out, thoughttypes.KeyCount{Key: pair.key, Count: pair.count})
	}
	return out
}