package database

import (
	"context"
	"database/sql"
	"fmt"

	_ "github.com/lib/pq"
)

// PostgresStore implements Store using PostgreSQL.
type PostgresStore struct {
	db *sql.DB
}

// NewPostgresStore creates a new PostgreSQL store.
func NewPostgresStore(connStr string) (*PostgresStore, error) {
	db, err := sql.Open("postgres", connStr)
	if err != nil {
		return nil, fmt.Errorf("failed to open database: %w", err)
	}

	if err := db.Ping(); err != nil {
		db.Close()
		return nil, fmt.Errorf("failed to ping database: %w", err)
	}

	return &PostgresStore{db: db}, nil
}

// Initialize creates or migrates the database schema.
func (s *PostgresStore) Initialize(ctx context.Context) error {
	// Check current schema version
	var version int
	err := s.db.QueryRowContext(ctx,
		"SELECT version FROM schema_info LIMIT 1").Scan(&version)

	needsRecreate := err != nil || version != SchemaVersion

	if needsRecreate {
		// Drop all tables in correct order (respecting foreign keys)
		dropStmts := []string{
			DropDeclarations,
			DropOptions,
			DropFiles,
			DropRevisions,
			DropSchemaInfo,
		}
		for _, stmt := range dropStmts {
			if _, err := s.db.ExecContext(ctx, stmt); err != nil {
				return fmt.Errorf("failed to drop table: %w", err)
			}
		}
	}

	// Create tables
	createStmts := []string{
		SchemaInfoTable,
		// PostgreSQL uses SERIAL for auto-increment
		`CREATE TABLE IF NOT EXISTS revisions (
			id SERIAL PRIMARY KEY,
			git_hash TEXT NOT NULL UNIQUE,
			channel_name TEXT,
			commit_date TIMESTAMP,
			indexed_at TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
			option_count INTEGER NOT NULL DEFAULT 0
		)`,
		`CREATE TABLE IF NOT EXISTS options (
			id SERIAL PRIMARY KEY,
			revision_id INTEGER NOT NULL REFERENCES revisions(id) ON DELETE CASCADE,
			name TEXT NOT NULL,
			parent_path TEXT NOT NULL,
			type TEXT,
			default_value TEXT,
			example TEXT,
			description TEXT,
			read_only BOOLEAN NOT NULL DEFAULT FALSE
		)`,
		`CREATE TABLE IF NOT EXISTS declarations (
			id SERIAL PRIMARY KEY,
			option_id INTEGER NOT NULL REFERENCES options(id) ON DELETE CASCADE,
			file_path TEXT NOT NULL,
			line INTEGER
		)`,
		`CREATE TABLE IF NOT EXISTS files (
			id SERIAL PRIMARY KEY,
			revision_id INTEGER NOT NULL REFERENCES revisions(id) ON DELETE CASCADE,
			file_path TEXT NOT NULL,
			extension TEXT,
			content TEXT NOT NULL
		)`,
		IndexOptionsRevisionName,
		IndexOptionsRevisionParent,
		IndexFilesRevisionPath,
		IndexDeclarationsOption,
	}

	for _, stmt := range createStmts {
		if _, err := s.db.ExecContext(ctx, stmt); err != nil {
			return fmt.Errorf("failed to create schema: %w", err)
		}
	}

	// Create full-text search index for PostgreSQL
	_, err = s.db.ExecContext(ctx, `
		CREATE INDEX IF NOT EXISTS idx_options_fts
		ON options USING GIN(to_tsvector('english', name || ' ' || COALESCE(description, '')))
	`)
	if err != nil {
		return fmt.Errorf("failed to create FTS index: %w", err)
	}

	// Set schema version
	if needsRecreate {
		_, err = s.db.ExecContext(ctx,
			"INSERT INTO schema_info (version) VALUES ($1)", SchemaVersion)
		if err != nil {
			return fmt.Errorf("failed to set schema version: %w", err)
		}
	}

	return nil
}

// Close closes the database connection.
func (s *PostgresStore) Close() error {
	return s.db.Close()
}

// CreateRevision creates a new revision record.
func (s *PostgresStore) CreateRevision(ctx context.Context, rev *Revision) error {
	err := s.db.QueryRowContext(ctx, `
		INSERT INTO revisions (git_hash, channel_name, commit_date, option_count)
		VALUES ($1, $2, $3, $4)
		RETURNING id, indexed_at`,
		rev.GitHash, rev.ChannelName, rev.CommitDate, rev.OptionCount,
	).Scan(&rev.ID, &rev.IndexedAt)
	if err != nil {
		return fmt.Errorf("failed to create revision: %w", err)
	}
	return nil
}

// GetRevision retrieves a revision by git hash.
func (s *PostgresStore) GetRevision(ctx context.Context, gitHash string) (*Revision, error) {
	rev := &Revision{}
	err := s.db.QueryRowContext(ctx, `
		SELECT id, git_hash, channel_name, commit_date, indexed_at, option_count
		FROM revisions WHERE git_hash = $1`, gitHash,
	).Scan(&rev.ID, &rev.GitHash, &rev.ChannelName, &rev.CommitDate, &rev.IndexedAt, &rev.OptionCount)
	if err == sql.ErrNoRows {
		return nil, nil
	}
	if err != nil {
		return nil, fmt.Errorf("failed to get revision: %w", err)
	}
	return rev, nil
}

// GetRevisionByChannel retrieves a revision by channel name.
func (s *PostgresStore) GetRevisionByChannel(ctx context.Context, channel string) (*Revision, error) {
	rev := &Revision{}
	err := s.db.QueryRowContext(ctx, `
		SELECT id, git_hash, channel_name, commit_date, indexed_at, option_count
		FROM revisions WHERE channel_name = $1
		ORDER BY indexed_at DESC LIMIT 1`, channel,
	).Scan(&rev.ID, &rev.GitHash, &rev.ChannelName, &rev.CommitDate, &rev.IndexedAt, &rev.OptionCount)
	if err == sql.ErrNoRows {
		return nil, nil
	}
	if err != nil {
		return nil, fmt.Errorf("failed to get revision by channel: %w", err)
	}
	return rev, nil
}

// ListRevisions returns all indexed revisions.
func (s *PostgresStore) ListRevisions(ctx context.Context) ([]*Revision, error) {
	rows, err := s.db.QueryContext(ctx, `
		SELECT id, git_hash, channel_name, commit_date, indexed_at, option_count
		FROM revisions ORDER BY indexed_at DESC`)
	if err != nil {
		return nil, fmt.Errorf("failed to list revisions: %w", err)
	}
	defer rows.Close()

	var revisions []*Revision
	for rows.Next() {
		rev := &Revision{}
		if err := rows.Scan(&rev.ID, &rev.GitHash, &rev.ChannelName, &rev.CommitDate, &rev.IndexedAt, &rev.OptionCount); err != nil {
			return nil, fmt.Errorf("failed to scan revision: %w", err)
		}
		revisions = append(revisions, rev)
	}
	return revisions, rows.Err()
}

// DeleteRevision removes a revision and all associated data.
func (s *PostgresStore) DeleteRevision(ctx context.Context, id int64) error {
	_, err := s.db.ExecContext(ctx, "DELETE FROM revisions WHERE id = $1", id)
	if err != nil {
		return fmt.Errorf("failed to delete revision: %w", err)
	}
	return nil
}

// UpdateRevisionOptionCount updates the option count for a revision.
func (s *PostgresStore) UpdateRevisionOptionCount(ctx context.Context, id int64, count int) error {
	_, err := s.db.ExecContext(ctx,
		"UPDATE revisions SET option_count = $1 WHERE id = $2", count, id)
	if err != nil {
		return fmt.Errorf("failed to update option count: %w", err)
	}
	return nil
}

// CreateOption creates a new option record.
func (s *PostgresStore) CreateOption(ctx context.Context, opt *Option) error {
	err := s.db.QueryRowContext(ctx, `
		INSERT INTO options (revision_id, name, parent_path, type, default_value, example, description, read_only)
		VALUES ($1, $2, $3, $4, $5, $6, $7, $8)
		RETURNING id`,
		opt.RevisionID, opt.Name, opt.ParentPath, opt.Type, opt.DefaultValue, opt.Example, opt.Description, opt.ReadOnly,
	).Scan(&opt.ID)
	if err != nil {
		return fmt.Errorf("failed to create option: %w", err)
	}
	return nil
}

// CreateOptionsBatch creates multiple options in a batch.
func (s *PostgresStore) CreateOptionsBatch(ctx context.Context, opts []*Option) error {
	tx, err := s.db.BeginTx(ctx, nil)
	if err != nil {
		return fmt.Errorf("failed to begin transaction: %w", err)
	}
	defer tx.Rollback()

	stmt, err := tx.PrepareContext(ctx, `
		INSERT INTO options (revision_id, name, parent_path, type, default_value, example, description, read_only)
		VALUES ($1, $2, $3, $4, $5, $6, $7, $8)
		RETURNING id`)
	if err != nil {
		return fmt.Errorf("failed to prepare statement: %w", err)
	}
	defer stmt.Close()

	for _, opt := range opts {
		err := stmt.QueryRowContext(ctx,
			opt.RevisionID, opt.Name, opt.ParentPath, opt.Type, opt.DefaultValue, opt.Example, opt.Description, opt.ReadOnly,
		).Scan(&opt.ID)
		if err != nil {
			return fmt.Errorf("failed to insert option %s: %w", opt.Name, err)
		}
	}

	return tx.Commit()
}

// GetOption retrieves an option by revision and name.
func (s *PostgresStore) GetOption(ctx context.Context, revisionID int64, name string) (*Option, error) {
	opt := &Option{}
	err := s.db.QueryRowContext(ctx, `
		SELECT id, revision_id, name, parent_path, type, default_value, example, description, read_only
		FROM options WHERE revision_id = $1 AND name = $2`, revisionID, name,
	).Scan(&opt.ID, &opt.RevisionID, &opt.Name, &opt.ParentPath, &opt.Type, &opt.DefaultValue, &opt.Example, &opt.Description, &opt.ReadOnly)
	if err == sql.ErrNoRows {
		return nil, nil
	}
	if err != nil {
		return nil, fmt.Errorf("failed to get option: %w", err)
	}
	return opt, nil
}

// GetChildren retrieves direct children of an option.
func (s *PostgresStore) GetChildren(ctx context.Context, revisionID int64, parentPath string) ([]*Option, error) {
	rows, err := s.db.QueryContext(ctx, `
		SELECT id, revision_id, name, parent_path, type, default_value, example, description, read_only
		FROM options WHERE revision_id = $1 AND parent_path = $2
		ORDER BY name`, revisionID, parentPath)
	if err != nil {
		return nil, fmt.Errorf("failed to get children: %w", err)
	}
	defer rows.Close()

	var options []*Option
	for rows.Next() {
		opt := &Option{}
		if err := rows.Scan(&opt.ID, &opt.RevisionID, &opt.Name, &opt.ParentPath, &opt.Type, &opt.DefaultValue, &opt.Example, &opt.Description, &opt.ReadOnly); err != nil {
			return nil, fmt.Errorf("failed to scan option: %w", err)
		}
		options = append(options, opt)
	}
	return options, rows.Err()
}

// SearchOptions searches for options matching a query.
func (s *PostgresStore) SearchOptions(ctx context.Context, revisionID int64, query string, filters SearchFilters) ([]*Option, error) {
	// Use PostgreSQL full-text search
	baseQuery := `
		SELECT id, revision_id, name, parent_path, type, default_value, example, description, read_only
		FROM options
		WHERE revision_id = $1
		AND to_tsvector('english', name || ' ' || COALESCE(description, '')) @@ plainto_tsquery('english', $2)`

	args := []interface{}{revisionID, query}
	argNum := 3

	if filters.Type != "" {
		baseQuery += fmt.Sprintf(" AND type = $%d", argNum)
		args = append(args, filters.Type)
		argNum++
	}

	if filters.Namespace != "" {
		baseQuery += fmt.Sprintf(" AND name LIKE $%d", argNum)
		args = append(args, filters.Namespace+"%")
		argNum++
	}

	if filters.HasDefault != nil {
		if *filters.HasDefault {
			baseQuery += " AND default_value IS NOT NULL"
		} else {
			baseQuery += " AND default_value IS NULL"
		}
	}

	baseQuery += " ORDER BY name"

	if filters.Limit > 0 {
		baseQuery += fmt.Sprintf(" LIMIT %d", filters.Limit)
	}
	if filters.Offset > 0 {
		baseQuery += fmt.Sprintf(" OFFSET %d", filters.Offset)
	}

	rows, err := s.db.QueryContext(ctx, baseQuery, args...)
	if err != nil {
		return nil, fmt.Errorf("failed to search options: %w", err)
	}
	defer rows.Close()

	var options []*Option
	for rows.Next() {
		opt := &Option{}
		if err := rows.Scan(&opt.ID, &opt.RevisionID, &opt.Name, &opt.ParentPath, &opt.Type, &opt.DefaultValue, &opt.Example, &opt.Description, &opt.ReadOnly); err != nil {
			return nil, fmt.Errorf("failed to scan option: %w", err)
		}
		options = append(options, opt)
	}
	return options, rows.Err()
}

// CreateDeclaration creates a new declaration record.
func (s *PostgresStore) CreateDeclaration(ctx context.Context, decl *Declaration) error {
	err := s.db.QueryRowContext(ctx, `
		INSERT INTO declarations (option_id, file_path, line)
		VALUES ($1, $2, $3)
		RETURNING id`,
		decl.OptionID, decl.FilePath, decl.Line,
	).Scan(&decl.ID)
	if err != nil {
		return fmt.Errorf("failed to create declaration: %w", err)
	}
	return nil
}

// CreateDeclarationsBatch creates multiple declarations in a batch.
func (s *PostgresStore) CreateDeclarationsBatch(ctx context.Context, decls []*Declaration) error {
	tx, err := s.db.BeginTx(ctx, nil)
	if err != nil {
		return fmt.Errorf("failed to begin transaction: %w", err)
	}
	defer tx.Rollback()

	stmt, err := tx.PrepareContext(ctx, `
		INSERT INTO declarations (option_id, file_path, line)
		VALUES ($1, $2, $3)
		RETURNING id`)
	if err != nil {
		return fmt.Errorf("failed to prepare statement: %w", err)
	}
	defer stmt.Close()

	for _, decl := range decls {
		err := stmt.QueryRowContext(ctx, decl.OptionID, decl.FilePath, decl.Line).Scan(&decl.ID)
		if err != nil {
			return fmt.Errorf("failed to insert declaration: %w", err)
		}
	}

	return tx.Commit()
}

// GetDeclarations retrieves declarations for an option.
func (s *PostgresStore) GetDeclarations(ctx context.Context, optionID int64) ([]*Declaration, error) {
	rows, err := s.db.QueryContext(ctx, `
		SELECT id, option_id, file_path, line
		FROM declarations WHERE option_id = $1`, optionID)
	if err != nil {
		return nil, fmt.Errorf("failed to get declarations: %w", err)
	}
	defer rows.Close()

	var decls []*Declaration
	for rows.Next() {
		decl := &Declaration{}
		if err := rows.Scan(&decl.ID, &decl.OptionID, &decl.FilePath, &decl.Line); err != nil {
			return nil, fmt.Errorf("failed to scan declaration: %w", err)
		}
		decls = append(decls, decl)
	}
	return decls, rows.Err()
}

// CreateFile creates a new file record.
func (s *PostgresStore) CreateFile(ctx context.Context, file *File) error {
	err := s.db.QueryRowContext(ctx, `
		INSERT INTO files (revision_id, file_path, extension, content)
		VALUES ($1, $2, $3, $4)
		RETURNING id`,
		file.RevisionID, file.FilePath, file.Extension, file.Content,
	).Scan(&file.ID)
	if err != nil {
		return fmt.Errorf("failed to create file: %w", err)
	}
	return nil
}

// CreateFilesBatch creates multiple files in a batch.
func (s *PostgresStore) CreateFilesBatch(ctx context.Context, files []*File) error {
	tx, err := s.db.BeginTx(ctx, nil)
	if err != nil {
		return fmt.Errorf("failed to begin transaction: %w", err)
	}
	defer tx.Rollback()

	stmt, err := tx.PrepareContext(ctx, `
		INSERT INTO files (revision_id, file_path, extension, content)
		VALUES ($1, $2, $3, $4)
		RETURNING id`)
	if err != nil {
		return fmt.Errorf("failed to prepare statement: %w", err)
	}
	defer stmt.Close()

	for _, file := range files {
		err := stmt.QueryRowContext(ctx, file.RevisionID, file.FilePath, file.Extension, file.Content).Scan(&file.ID)
		if err != nil {
			return fmt.Errorf("failed to insert file: %w", err)
		}
	}

	return tx.Commit()
}

// GetFile retrieves a file by revision and path.
func (s *PostgresStore) GetFile(ctx context.Context, revisionID int64, path string) (*File, error) {
	file := &File{}
	err := s.db.QueryRowContext(ctx, `
		SELECT id, revision_id, file_path, extension, content
		FROM files WHERE revision_id = $1 AND file_path = $2`, revisionID, path,
	).Scan(&file.ID, &file.RevisionID, &file.FilePath, &file.Extension, &file.Content)
	if err == sql.ErrNoRows {
		return nil, nil
	}
	if err != nil {
		return nil, fmt.Errorf("failed to get file: %w", err)
	}
	return file, nil
}