Implement sql query builder

server/internal/db/query.go

@@ -0,0 +1,263 @@
+package db
+
+import (
+	"fmt"
+	"strings"
+)
+
+type JoinType string
+
+const (
+	InnerJoin JoinType = "INNER JOIN"
+	LeftJoin  JoinType = "LEFT JOIN"
+	RightJoin JoinType = "RIGHT JOIN"
+)
+
+// Query represents a SQL query with its parameters
+type Query struct {
+	builder     strings.Builder
+	args        []interface{}
+	dbType      DBType
+	pos         int // tracks the current placeholder position
+	hasSelect   bool
+	hasFrom     bool
+	hasWhere    bool
+	hasOrderBy  bool
+	hasGroupBy  bool
+	hasLimit    bool
+	hasOffset   bool
+	isInParens  bool
+	parensDepth int
+}
+
+// NewQuery creates a new Query instance
+func NewQuery(dbType DBType) *Query {
+	return &Query{
+		dbType: dbType,
+		args:   make([]interface{}, 0),
+	}
+}
+
+// Select adds a SELECT clause
+func (q *Query) Select(columns ...string) *Query {
+	if !q.hasSelect {
+		q.Write("SELECT ")
+		q.Write(strings.Join(columns, ", "))
+		q.hasSelect = true
+	}
+	return q
+}
+
+// From adds a FROM clause
+func (q *Query) From(table string) *Query {
+	if !q.hasFrom {
+		q.Write(" FROM ")
+		q.Write(table)
+		q.hasFrom = true
+	}
+	return q
+}
+
+// Where adds a WHERE clause
+func (q *Query) Where(condition string) *Query {
+	if !q.hasWhere {
+		q.Write(" WHERE ")
+		q.hasWhere = true
+	} else {
+		q.Write(" AND ")
+	}
+	q.Write(condition)
+	return q
+}
+
+// WhereIn adds a WHERE IN clause
+func (q *Query) WhereIn(column string, count int) *Query {
+	if !q.hasWhere {
+		q.Write(" WHERE ")
+		q.hasWhere = true
+	} else {
+		q.Write(" AND ")
+	}
+	q.Write(column)
+	q.Write(" IN (")
+	q.Placeholders(count)
+	q.Write(")")
+	return q
+}
+
+// And adds an AND condition
+func (q *Query) And(condition string) *Query {
+	q.Write(" AND ")
+	q.Write(condition)
+	return q
+}
+
+// Or adds an OR condition
+func (q *Query) Or(condition string) *Query {
+	q.Write(" OR ")
+	q.Write(condition)
+	return q
+}
+
+// Join adds a JOIN clause
+func (q *Query) Join(joinType JoinType, table, condition string) *Query {
+	q.Write(" ")
+	q.Write(string(joinType))
+	q.Write(" ")
+	q.Write(table)
+	q.Write(" ON ")
+	q.Write(condition)
+	return q
+}
+
+// OrderBy adds an ORDER BY clause
+func (q *Query) OrderBy(columns ...string) *Query {
+	if !q.hasOrderBy {
+		q.Write(" ORDER BY ")
+		q.Write(strings.Join(columns, ", "))
+		q.hasOrderBy = true
+	}
+	return q
+}
+
+// GroupBy adds a GROUP BY clause
+func (q *Query) GroupBy(columns ...string) *Query {
+	if !q.hasGroupBy {
+		q.Write(" GROUP BY ")
+		q.Write(strings.Join(columns, ", "))
+		q.hasGroupBy = true
+	}
+	return q
+}
+
+// Limit adds a LIMIT clause
+func (q *Query) Limit(limit int) *Query {
+	if !q.hasLimit {
+		q.Write(" LIMIT ")
+		q.Write(fmt.Sprintf("%d", limit))
+		q.hasLimit = true
+	}
+	return q
+}
+
+// Offset adds an OFFSET clause
+func (q *Query) Offset(offset int) *Query {
+	if !q.hasOffset {
+		q.Write(" OFFSET ")
+		q.Write(fmt.Sprintf("%d", offset))
+		q.hasOffset = true
+	}
+	return q
+}
+
+// Insert starts an INSERT statement
+func (q *Query) Insert(table string, columns ...string) *Query {
+	q.Write("INSERT INTO ")
+	q.Write(table)
+	q.Write(" (")
+	q.Write(strings.Join(columns, ", "))
+	q.Write(") VALUES ")
+	return q
+}
+
+// Values adds a VALUES clause
+func (q *Query) Values(count int) *Query {
+	q.Write("(")
+	q.Placeholders(count)
+	q.Write(")")
+	return q
+}
+
+// Update starts an UPDATE statement
+func (q *Query) Update(table string) *Query {
+	q.Write("UPDATE ")
+	q.Write(table)
+	q.Write(" SET ")
+	return q
+}
+
+// Set adds a SET clause for updates
+func (q *Query) Set(column string) *Query {
+	if strings.Contains(q.builder.String(), "SET ") &&
+		!strings.HasSuffix(q.builder.String(), "SET ") {
+		q.Write(", ")
+	}
+	q.Write(column)
+	q.Write(" = ")
+	return q
+}
+
+// Delete starts a DELETE statement
+func (q *Query) Delete() *Query {
+	q.Write("DELETE")
+	return q
+}
+
+// StartGroup starts a parenthetical group
+func (q *Query) StartGroup() *Query {
+	q.Write(" (")
+	q.parensDepth++
+	return q
+}
+
+// EndGroup ends a parenthetical group
+func (q *Query) EndGroup() *Query {
+	if q.parensDepth > 0 {
+		q.Write(")")
+		q.parensDepth--
+	}
+	return q
+}
+
+// Write adds a string to the query
+func (q *Query) Write(s string) *Query {
+	q.builder.WriteString(s)
+	return q
+}
+
+// Placeholder adds a placeholder for a single argument
+func (q *Query) Placeholder(arg interface{}) *Query {
+	q.pos++
+	q.args = append(q.args, arg)
+
+	if q.dbType == DBTypePostgres {
+		q.builder.WriteString(fmt.Sprintf("$%d", q.pos))
+	} else {
+		q.builder.WriteString("?")
+	}
+
+	return q
+}
+
+// Placeholders adds n placeholders separated by commas
+func (q *Query) Placeholders(n int) *Query {
+	placeholders := make([]string, n)
+
+	for i := 0; i < n; i++ {
+		q.pos++
+		if q.dbType == DBTypePostgres {
+			placeholders[i] = fmt.Sprintf("$%d", q.pos)
+		} else {
+			placeholders[i] = "?"
+		}
+	}
+
+	q.builder.WriteString(strings.Join(placeholders, ", "))
+	return q
+}
+
+// AddArgs adds arguments to the query
+func (q *Query) AddArgs(args ...interface{}) *Query {
+	q.args = append(q.args, args...)
+	return q
+}
+
+// String returns the formatted query string
+func (q *Query) String() string {
+	return q.builder.String()
+}
+
+// Args returns the query arguments
+func (q *Query) Args() []interface{} {
+	return q.args
+}