package writers

import (
	"fmt"
	"strings"

	"git.warky.dev/wdevs/relspecgo/pkg/pgsql"
)

// ParseTypeMappings parses "sqltype=gotype" entries (as given to --type-map)
// into a map keyed by the canonical lower-case SQL base type, so that
// "VARCHAR", "character varying" and "varchar(50)" all address one entry.
// It returns nil for empty input.
func ParseTypeMappings(entries []string) (map[string]string, error) {
	if len(entries) == 0 {
		return nil, nil
	}
	out := make(map[string]string, len(entries))
	for _, entry := range entries {
		sqlType, goType, ok := strings.Cut(entry, "=")
		sqlType, goType = strings.TrimSpace(sqlType), strings.TrimSpace(goType)
		if !ok || sqlType == "" || goType == "" {
			return nil, fmt.Errorf("invalid type mapping %q: expected sqltype=gotype", entry)
		}
		out[pgsql.CanonicalizeBaseType(pgsql.ExtractBaseTypeLower(sqlType))] = goType
	}
	return out, nil
}

// LookupTypeMapping returns the user-configured override for baseType, which
// the caller must already have canonicalized.
func LookupTypeMapping(mappings map[string]string, baseType string) (string, bool) {
	goType, ok := mappings[baseType]
	return goType, ok
}

// ApplyTypeMapping wraps an overridden Go type for nullability: NOT NULL uses
// the type verbatim; nullable columns get a pointer prefix unless the type is
// already a pointer, slice, map or interface.
func ApplyTypeMapping(goType string, notNull bool) string {
	if notNull || strings.HasPrefix(goType, "*") || strings.HasPrefix(goType, "[]") ||
		strings.HasPrefix(goType, "map[") || goType == "any" || goType == "interface{}" {
		return goType
	}
	return "*" + goType
}