package install

import (
	"context"
	"embed"
	"fmt"
	"io/fs"
	"sort"
	"strings"

	"git.warky.dev/wdevs/pgsql-broker/pkg/broker/adapter"
)

//go:embed all:sql
var sqlFS embed.FS

// Installer handles database schema installation
type Installer struct {
	db     adapter.DBAdapter
	logger adapter.Logger
}

// New creates a new installer
func New(db adapter.DBAdapter, logger adapter.Logger) *Installer {
	return &Installer{
		db:     db,
		logger: logger,
	}
}

// InstallSchema installs the complete database schema
func (i *Installer) InstallSchema(ctx context.Context) error {
	i.logger.Info("starting schema installation")

	// Install tables first
	if err := i.installTables(ctx); err != nil {
		return fmt.Errorf("failed to install tables: %w", err)
	}

	// Then install procedures
	if err := i.installProcedures(ctx); err != nil {
		return fmt.Errorf("failed to install procedures: %w", err)
	}

	i.logger.Info("schema installation completed successfully")
	return nil
}

// installTables installs all table definitions
func (i *Installer) installTables(ctx context.Context) error {
	i.logger.Info("installing tables")

	files, err := sqlFS.ReadDir("sql/tables")
	if err != nil {
		return fmt.Errorf("failed to read tables directory: %w", err)
	}

	// Filter and sort SQL files
	sqlFiles := filterAndSortSQLFiles(files)

	for _, file := range sqlFiles {
		// Skip install script
		if file == "00_install.sql" {
			continue
		}

		i.logger.Info("executing table script", "file", file)

		content, err := sqlFS.ReadFile("sql/tables/" + file)
		if err != nil {
			return fmt.Errorf("failed to read file %s: %w", file, err)
		}

		if err := i.executeSQL(ctx, string(content)); err != nil {
			return fmt.Errorf("failed to execute %s: %w", file, err)
		}
	}

	i.logger.Info("tables installed successfully")
	return nil
}

// installProcedures installs all stored procedures
func (i *Installer) installProcedures(ctx context.Context) error {
	i.logger.Info("installing procedures")

	files, err := sqlFS.ReadDir("sql/procedures")
	if err != nil {
		return fmt.Errorf("failed to read procedures directory: %w", err)
	}

	// Filter and sort SQL files
	sqlFiles := filterAndSortSQLFiles(files)

	for _, file := range sqlFiles {
		// Skip install script
		if file == "00_install.sql" {
			continue
		}

		i.logger.Info("executing procedure script", "file", file)

		content, err := sqlFS.ReadFile("sql/procedures/" + file)
		if err != nil {
			return fmt.Errorf("failed to read file %s: %w", file, err)
		}

		if err := i.executeSQL(ctx, string(content)); err != nil {
			return fmt.Errorf("failed to execute %s: %w", file, err)
		}
	}

	i.logger.Info("procedures installed successfully")
	return nil
}

// executeSQL executes SQL statements
func (i *Installer) executeSQL(ctx context.Context, sql string) error {
	// Remove comments and split by statement
	statements := splitSQLStatements(sql)

	for _, stmt := range statements {
		stmt = strings.TrimSpace(stmt)
		if stmt == "" {
			continue
		}

		// Skip psql-specific commands
		if strings.HasPrefix(stmt, "\\") {
			continue
		}

		if _, err := i.db.Exec(ctx, stmt); err != nil {
			return fmt.Errorf("failed to execute statement: %w\nStatement: %s", err, stmt)
		}
	}

	return nil
}

// filterAndSortSQLFiles filters and sorts SQL files
func filterAndSortSQLFiles(files []fs.DirEntry) []string {
	var sqlFiles []string
	for _, file := range files {
		if !file.IsDir() && strings.HasSuffix(file.Name(), ".sql") {
			sqlFiles = append(sqlFiles, file.Name())
		}
	}
	sort.Strings(sqlFiles)
	return sqlFiles
}

// splitSQLStatements splits SQL into individual statements
func splitSQLStatements(sql string) []string {
	// Simple split by semicolon
	// This doesn't handle all edge cases (strings with semicolons, dollar-quoted strings, etc.)
	// but works for our use case
	statements := strings.Split(sql, ";")

	var result []string
	var buffer string

	for _, stmt := range statements {
		stmt = strings.TrimSpace(stmt)
		if stmt == "" {
			continue
		}

		buffer += stmt + ";"

		// Check if we're inside a function definition ($$)
		dollarCount := strings.Count(buffer, "$$")
		if dollarCount%2 == 0 {
			// Even number of $$ means we're outside function definitions
			result = append(result, buffer)
			buffer = ""
		} else {
			// Odd number means we're inside a function, keep accumulating
			buffer += " "
		}
	}

	// Add any remaining buffered content
	if buffer != "" {
		result = append(result, buffer)
	}

	return result
}

// VerifyInstallation checks if the schema is properly installed
func (i *Installer) VerifyInstallation(ctx context.Context) error {
	i.logger.Info("verifying installation")

	tables := []string{"broker_queueinstance", "broker_jobs", "broker_schedule"}
	procedures := []string{
		"broker_get",
		"broker_run",
		"broker_set",
		"broker_add_job",
		"broker_register_instance",
		"broker_ping_instance",
		"broker_shutdown_instance",
	}

	// Check tables
	for _, table := range tables {
		var exists bool
		err := i.db.QueryRow(ctx,
			"SELECT EXISTS (SELECT FROM information_schema.tables WHERE table_name = $1)",
			table,
		).Scan(&exists)

		if err != nil {
			return fmt.Errorf("failed to check table %s: %w", table, err)
		}

		if !exists {
			return fmt.Errorf("table %s does not exist", table)
		}

		i.logger.Info("table verified", "table", table)
	}

	// Check procedures
	for _, proc := range procedures {
		var exists bool
		err := i.db.QueryRow(ctx,
			"SELECT EXISTS (SELECT FROM pg_proc WHERE proname = $1)",
			proc,
		).Scan(&exists)

		if err != nil {
			return fmt.Errorf("failed to check procedure %s: %w", proc, err)
		}

		if !exists {
			return fmt.Errorf("procedure %s does not exist", proc)
		}

		i.logger.Info("procedure verified", "procedure", proc)
	}

	i.logger.Info("installation verified successfully")
	return nil
}