pgm/qry.go

// Patial Tech.
// Author, Ankit Patial

package pgm

import (
	"context"
	"strconv"
	"strings"

	"github.com/jackc/pgx/v5"
)

type (
	Clause interface {
		Select(fields ...Field) SelectClause
		// Insert() InsertSet
		// Update() UpdateSet
		// Delete() WhereOrExec
	}

	SelectClause interface {
		// Join and Inner Join are same
		Join(m Table, t1Field, t2Field Field) SelectClause
		LeftJoin(m Table, t1Field, t2Field Field) SelectClause
		RightJoin(m Table, t1Field, t2Field Field) SelectClause
		FullJoin(m Table, t1Field, t2Field Field) SelectClause
		CrossJoin(m Table) SelectClause
		WhereClause
		OrderByClause
		GroupByClause
		LimitClause
		OffsetClause
		Query
		raw(prefixArgs []any) (string, []any)
	}

	WhereClause interface {
		Where(cond ...Conditioner) AfterWhere
	}

	AfterWhere interface {
		WhereClause
		GroupByClause
		OrderByClause
		LimitClause
		OffsetClause
		Query
	}

	GroupByClause interface {
		GroupBy(fields ...Field) AfterGroupBy
	}

	AfterGroupBy interface {
		HavinClause
		OrderByClause
		LimitClause
		OffsetClause
		Query
	}

	HavinClause interface {
		Having(cond ...Conditioner) AfterHaving
	}

	AfterHaving interface {
		OrderByClause
		LimitClause
		OffsetClause
		Query
	}

	OrderByClause interface {
		OrderBy(fields ...Field) AfterOrderBy
	}

	AfterOrderBy interface {
		LimitClause
		OffsetClause
		Query
	}

	LimitClause interface {
		Limit(v int) AfterLimit
	}

	AfterLimit interface {
		OffsetClause
		Query
	}

	OffsetClause interface {
		Offset(v int) AfterOffset
	}

	AfterOffset interface {
		LimitClause
		Query
	}

	Conditioner interface {
		Condition(args *[]any, idx int) string
	}

	Insert interface {
		Set(field Field, val any) InsertClause
		SetMap(fields map[Field]any) InsertClause
	}

	InsertClause interface {
		Insert
		Returning(field Field) First
		OnConflict(fields ...Field) Do
		Execute
		Stringer
	}

	Do interface {
		DoNothing() Execute
		DoUpdate(fields ...Field) Execute
	}

	Update interface {
		Set(field Field, val any) UpdateClause
		SetMap(fields map[Field]any) UpdateClause
	}

	UpdateClause interface {
		Update
		Where(cond ...Conditioner) WhereOrExec
	}

	WhereOrExec interface {
		Where(cond ...Conditioner) WhereOrExec
		Execute
	}

	Query interface {
		First
		All
		Stringer
	}

	First interface {
		First(ctx context.Context, dest ...any) error
		FirstTx(ctx context.Context, tx pgx.Tx, dest ...any) error
		Stringer
	}

	All interface {
		// Query rows
		//
		// don't forget to close() rows
		All(ctx context.Context, rows RowsCb) error
		// Query rows
		//
		// don't forget to close() rows
		AllTx(ctx context.Context, tx pgx.Tx, rows RowsCb) error
	}

	Execute interface {
		Exec(ctx context.Context) error
		ExecTx(ctx context.Context, tx pgx.Tx) error
		Stringer
	}

	Stringer interface {
		String() string
	}

	RowScanner interface {
		Scan(dest ...any) error
	}

	RowsCb func(row RowScanner) error
)

func joinFileds(fields []Field) string {
	sb := getSB()
	defer putSB(sb)
	for i, f := range fields {
		if i == 0 {
			sb.WriteString(f.String())
		} else {
			sb.WriteString(", ")
			sb.WriteString(f.String())
		}
	}

	return sb.String()
}

func And(cond ...Conditioner) Conditioner {
	return &CondGroup{op: " AND ", cond: cond}
}

func Or(cond ...Conditioner) Conditioner {
	return &CondGroup{op: " OR ", cond: cond}
}

func (cv *Cond) Condition(args *[]any, argIdx int) string {
	// 1. condition with subquery
	if cv.action == CondActionSubQuery {
		qStr, newArgs := cv.Val.(SelectClause).raw(*args)
		*args = newArgs
		return cv.Field + strings.Replace(cv.op, "$", qStr, 1)
	}

	// 2. normal condition
	var op string
	if cv.Val != nil {
		*args = append(*args, cv.Val)
		if strings.HasSuffix(cv.op, "$") {
			op = cv.op + strconv.Itoa(argIdx+1)
		} else {
			op = strings.Replace(cv.op, "$", "$"+strconv.Itoa(argIdx+1), 1)
		}
	} else {
		op = cv.op
	}

	if cv.action == CondActionNeedToClose {
		return cv.Field + op + ")"
	}
	return cv.Field + op
}

func (c *CondGroup) Condition(args *[]any, argIdx int) string {
	sb := getSB()
	defer putSB(sb)

	sb.WriteString("(")
	for i, cond := range c.cond {
		if i == 0 {
			sb.WriteString(cond.Condition(args, argIdx+i))
		} else {
			sb.WriteString(c.op)
			sb.WriteString(cond.Condition(args, argIdx+i))
		}
	}
	sb.WriteString(")")
	return sb.String()
}