// Package clause provides the clause interface and common clause implementations for GORM.
package clause

// Interface clause interface
type Interface interface {
	Name() string
	Build(Builder)
	MergeClause(*Clause)
}

// ClauseBuilder clause builder, allows to customize how to build clause
type ClauseBuilder func(Clause, Builder)

type Writer interface {
	WriteByte(byte) error
	WriteString(string) (int, error)
}

SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS

package clause

// GroupBy group by clause
type GroupBy struct {
	Columns []Column
	Having  []Expression
}

// Name from clause name
func (groupBy GroupBy) Name() string {
	return "GROUP BY"
}

// Build build group by clause
func (groupBy GroupBy) Build(builder Builder) {
	for idx, column := range groupBy.Columns {
		if idx > 0 {
			builder.WriteByte(',')
		}

		builder.WriteQuoted(column)
	}

	}
}

// MergeClause merge order by clauses
func (returning Returning) MergeClause(clause *Clause) {
	if v, ok := clause.Expression.(Returning); ok && len(returning.Columns) > 0 {
		if v.Columns != nil {
			returning.Columns = append(v.Columns, returning.Columns...)
		} else {
			returning.Columns = nil
		}
	}
	clause.Expression = returning

	}

	if len(onConflict.Where.Exprs) > 0 {
		builder.WriteString(" WHERE ")
		onConflict.Where.Build(builder)
		builder.WriteByte(' ')
	}
}

// MergeClause merge onConflict clauses
func (onConflict OnConflict) MergeClause(clause *Clause) {
	clause.Expression = onConflict

		builder.WriteQuoted(locking.Table)
	}

	if locking.Options != "" {
		builder.WriteByte(' ')
		builder.WriteString(locking.Options)
	}
}

// MergeClause merge order by clauses
func (locking Locking) MergeClause(clause *Clause) {
	clause.Expression = locking

	} else {
		builder.WriteQuoted(insert.Table)
	}
}

// MergeClause merge insert clause
func (insert Insert) MergeClause(clause *Clause) {
	if v, ok := clause.Expression.(Insert); ok {
		if insert.Modifier == "" {
			insert.Modifier = v.Modifier
		}
		if insert.Table.Name == "" {
			insert.Table = v.Table
		}
	}
	clause.Expression = insert

			builder.AddVar(builder, value...)
			builder.WriteByte(')')
		}
	} else {
		builder.WriteString("DEFAULT VALUES")
	}
}

// MergeClause merge values clauses
func (values Values) MergeClause(clause *Clause) {
	clause.Name = ""
	clause.Expression = values

		} else {
			expr.Build(builder)
		}
	}
}

// MergeClause merge where clauses
func (where Where) MergeClause(clause *Clause) {
	if w, ok := clause.Expression.(Where); ok {
		exprs := make([]Expression, len(w.Exprs)+len(where.Exprs))
		copy(exprs, w.Exprs)
		copy(exprs[len(w.Exprs):], where.Exprs)
		where.Exprs = exprs
	}

	clause.Expression = where
}

func And(exprs ...Expression) Expression {

	}
}

// MergeClause merge update clause
func (update Update) MergeClause(clause *Clause) {
	if v, ok := clause.Expression.(Update); ok {
		if update.Modifier == "" {
			update.Modifier = v.Modifier
		}
		if update.Table.Name == "" {
			update.Table = v.Table
		}
	}
	clause.Expression = update