package orm

import (
	"reflect"

	"github.com/go-pg/pg/v10/types"
)

type DeleteQuery struct {
	q           *Query
	placeholder bool
}

var (
	_ QueryAppender = (*DeleteQuery)(nil)
	_ QueryCommand  = (*DeleteQuery)(nil)
)

func NewDeleteQuery(q *Query) *DeleteQuery {
	return &DeleteQuery{
		q: q,
	}
}

func (q *DeleteQuery) String() string {
	b, err := q.AppendQuery(defaultFmter, nil)
	if err != nil {
		panic(err)
	}
	return string(b)
}

func (q *DeleteQuery) Operation() QueryOp {
	return DeleteOp
}

func (q *DeleteQuery) Clone() QueryCommand {
	return &DeleteQuery{
		q:           q.q.Clone(),
		placeholder: q.placeholder,
	}
}

func (q *DeleteQuery) Query() *Query {
	return q.q
}

func (q *DeleteQuery) AppendTemplate(b []byte) ([]byte, error) {
	cp := q.Clone().(*DeleteQuery)
	cp.placeholder = true
	return cp.AppendQuery(dummyFormatter{}, b)
}

func (q *DeleteQuery) AppendQuery(fmter QueryFormatter, b []byte) (_ []byte, err error) {
	if q.q.stickyErr != nil {
		return nil, q.q.stickyErr
	}

	if len(q.q.with) > 0 {
		b, err = q.q.appendWith(fmter, b)
		if err != nil {
			return nil, err
		}
	}

	b = append(b, "DELETE FROM "...)
	b, err = q.q.appendFirstTableWithAlias(fmter, b)
	if err != nil {
		return nil, err
	}

	if q.q.hasMultiTables() {
		b = append(b, " USING "...)
		b, err = q.q.appendOtherTables(fmter, b)
		if err != nil {
			return nil, err
		}
	}

	b = append(b, " WHERE "...)
	value := q.q.tableModel.Value()

	if q.q.isSliceModelWithData() {
		if len(q.q.where) > 0 {
			b, err = q.q.appendWhere(fmter, b)
			if err != nil {
				return nil, err
			}
		} else {
			table := q.q.tableModel.Table()
			err = table.checkPKs()
			if err != nil {
				return nil, err
			}

			b = appendColumnAndSliceValue(fmter, b, value, table.Alias, table.PKs)
		}
	} else {
		b, err = q.q.mustAppendWhere(fmter, b)
		if err != nil {
			return nil, err
		}
	}

	if len(q.q.returning) > 0 {
		b, err = q.q.appendReturning(fmter, b)
		if err != nil {
			return nil, err
		}
	}

	return b, q.q.stickyErr
}

func appendColumnAndSliceValue(
	fmter QueryFormatter, b []byte, slice reflect.Value, alias types.Safe, fields []*Field,
) []byte {
	if len(fields) > 1 {
		b = append(b, '(')
	}
	b = appendColumns(b, alias, fields)
	if len(fields) > 1 {
		b = append(b, ')')
	}

	b = append(b, " IN ("...)

	isPlaceholder := isTemplateFormatter(fmter)
	sliceLen := slice.Len()
	for i := 0; i < sliceLen; i++ {
		if i > 0 {
			b = append(b, ", "...)
		}

		el := indirect(slice.Index(i))

		if len(fields) > 1 {
			b = append(b, '(')
		}
		for i, f := range fields {
			if i > 0 {
				b = append(b, ", "...)
			}
			if isPlaceholder {
				b = append(b, '?')
			} else {
				b = f.AppendValue(b, el, 1)
			}
		}
		if len(fields) > 1 {
			b = append(b, ')')
		}
	}

	b = append(b, ')')

	return b
}