package schema

import (
	"reflect"
	"strings"

	"git.gdulai.com/gdulai/simpleorm/util"
	log "gitlab.com/gdulai/simpleloglvl"
)

type Parser struct {
	typ         reflect.Type
	columns     []Column
	constraints []Constraint
}

func NewParser[T any](obj T) *Parser {
	objType := reflect.TypeOf(obj)
	return &Parser{typ: objType}
}

// Step 1 of the parsing, it creates the table instance and
func (p *Parser) ParseColumns() {
	var columns []Column
	for field := range p.typ.Fields() {
		field := field
		col := NewColumn(util.CamelToSnake((field.Name)), field.Name, determineType(field.Type), field.Tag)
		columns = append(columns, col)
	}
	p.columns = columns
}

// Step 2 of the parsing, it creates the constrains with the table references
func (p *Parser) ParseConstraints(tableParsers map[string]*Parser) {
	pkConstraint := Constraint{Name: "pk_" + strings.ToLower(util.CamelToSnake((p.typ.Name()))), Type: "pk"}
	fkConstraints := make(map[string]Constraint)
	for _, col := range p.columns {
		_, ok := col.Modifiers["pk"]
		if ok {
			pkConstraint.Columns = append(pkConstraint.Columns, col)
			continue
		}

		fkMod, ok := col.Modifiers["fk"]
		if !ok {
			continue
		}

		fkModParts := strings.Split(fkMod, ".")
		refTypeName := fkModParts[0]
		refTableName := util.CamelToSnake(refTypeName)
		parser, ok := tableParsers[refTypeName]
		if !ok {
			log.LogError("[ORM] Reference table not found", refTypeName)
		}

		fkId, ok := col.Modifiers["fk_id"]
		if fkId == "" {
			fkId = "fk_" + strings.ToLower(refTableName)
		}

		fkConstraint, ok := fkConstraints[fkId]
		if !ok {
			fkConstraint = Constraint{Name: fkId, Type: "fk", RefTypeName: refTypeName}
		}

		fkConstraint.Columns = append(fkConstraint.Columns, col)

		refField := fkModParts[1]
		for _, refC := range parser.columns {
			if refC.FieldName == refField {
				fkConstraint.RefColumns = append(fkConstraint.RefColumns, refC)
			}
		}

		fkConstraints[fkId] = fkConstraint
	}

	p.constraints = append(p.constraints, pkConstraint)
	for _, fkConstraint := range fkConstraints {
		p.constraints = append(p.constraints, fkConstraint)
	}
}

// Step 3 of the paring, create the schema.Table instance
// Returns the schema.Table pointer
func (p Parser) ParseTable() *Table {
	return &Table{name: util.CamelToSnake(p.typ.Name()), typ: p.typ, columns: p.columns, constraints: p.constraints}
}

func determineType(typ reflect.Type) string {
	typStr := typ.String()
	switch typStr {
	case "string":
		return "TEXT"
	case "int", "bool":
		return "INTEGER"
	case "time.Time", "int64":
		return "BIGINT"
	}

	return "VARCHAR(255)"
}