package sqlite

import (
	"fmt"
	"strings"
	"text/template"

	"git.warky.dev/wdevs/relspecgo/pkg/models"
	"git.warky.dev/wdevs/relspecgo/pkg/writers"
)

// GetTemplateFuncs returns template functions for SQLite SQL generation
func GetTemplateFuncs(opts *writers.WriterOptions) template.FuncMap {
	return template.FuncMap{
		"quote_ident":      QuoteIdentifier,
		"map_type":         MapPostgreSQLType,
		"is_autoincrement": IsAutoIncrementCandidate,
		"qualified_table_name": func(schema, table string) string {
			return writers.QualifiedTableName(schema, table, opts.FlattenSchema)
		},
		"format_default": FormatDefault,
		"format_constraint_name": func(schema, table, constraint string) string {
			return FormatConstraintName(schema, table, constraint, opts)
		},
		"join":  strings.Join,
		"lower": strings.ToLower,
		"upper": strings.ToUpper,
	}
}

// QuoteIdentifier quotes an identifier for SQLite (double quotes)
func QuoteIdentifier(name string) string {
	// SQLite uses double quotes for identifiers
	// Escape any existing double quotes by doubling them
	escaped := strings.ReplaceAll(name, `"`, `""`)
	return fmt.Sprintf(`"%s"`, escaped)
}

// IsAutoIncrementCandidate checks if a column should use AUTOINCREMENT
func IsAutoIncrementCandidate(col *models.Column) bool {
	// Must be a primary key
	if !col.IsPrimaryKey {
		return false
	}

	// Must be an integer type
	if !IsIntegerType(col.Type) {
		return false
	}

	// Check AutoIncrement field
	if col.AutoIncrement {
		return true
	}

	// Check if default suggests auto-increment
	if col.Default != nil {
		defaultStr, ok := col.Default.(string)
		if ok {
			defaultLower := strings.ToLower(defaultStr)
			if strings.Contains(defaultLower, "nextval") ||
				strings.Contains(defaultLower, "autoincrement") ||
				strings.Contains(defaultLower, "auto_increment") {
				return true
			}
		}
	}

	// Serial types are auto-increment
	typeLower := strings.ToLower(col.Type)
	return strings.Contains(typeLower, "serial")
}

// FormatDefault formats a default value for SQLite
func FormatDefault(col *models.Column) string {
	if col.Default == nil {
		return ""
	}

	// Skip auto-increment defaults (handled by AUTOINCREMENT keyword)
	if IsAutoIncrementCandidate(col) {
		return ""
	}

	// Convert to string
	defaultStr, ok := col.Default.(string)
	if !ok {
		// If not a string, convert to string representation
		defaultStr = fmt.Sprintf("%v", col.Default)
	}

	if defaultStr == "" {
		return ""
	}

	// Convert PostgreSQL-specific functions to SQLite equivalents
	defaultLower := strings.ToLower(defaultStr)

	// Current timestamp functions
	if strings.Contains(defaultLower, "current_timestamp") ||
		strings.Contains(defaultLower, "now()") {
		return "CURRENT_TIMESTAMP"
	}

	// Current date
	if strings.Contains(defaultLower, "current_date") {
		return "CURRENT_DATE"
	}

	// Current time
	if strings.Contains(defaultLower, "current_time") {
		return "CURRENT_TIME"
	}

	// Boolean values
	sqliteType := MapPostgreSQLType(col.Type)
	if sqliteType == TypeInteger {
		typeLower := strings.ToLower(col.Type)
		if strings.Contains(typeLower, "bool") {
			return MapBooleanValue(defaultStr)
		}
	}

	// UUID generation - SQLite doesn't have built-in UUID, comment it out
	if strings.Contains(defaultLower, "uuid") || strings.Contains(defaultLower, "gen_random_uuid") {
		return "" // Remove UUID defaults, users must handle this
	}

	// Remove PostgreSQL-specific casting
	defaultStr = strings.ReplaceAll(defaultStr, "::text", "")
	defaultStr = strings.ReplaceAll(defaultStr, "::integer", "")
	defaultStr = strings.ReplaceAll(defaultStr, "::bigint", "")
	defaultStr = strings.ReplaceAll(defaultStr, "::boolean", "")

	return defaultStr
}

// FormatConstraintName formats a constraint name with table prefix if flattening
func FormatConstraintName(schema, table, constraint string, opts *writers.WriterOptions) string {
	if opts.FlattenSchema && schema != "" {
		// Prefix constraint with flattened table name
		flatTable := writers.QualifiedTableName(schema, table, opts.FlattenSchema)
		return fmt.Sprintf("%s_%s", flatTable, constraint)
	}
	return constraint
}