1 files changed, 411 insertions, 0 deletions
diff --git a/vendor/github.com/uptrace/bun/migrate/diff.go b/vendor/github.com/uptrace/bun/migrate/diff.go
new file mode 100644
index 000000000..42e55dcde
--- /dev/null
+++ b/vendor/github.com/uptrace/bun/migrate/diff.go
@@ -0,0 +1,411 @@
+package migrate
+
+import (
+	"github.com/uptrace/bun/migrate/sqlschema"
+)
+
+// changeset is a set of changes to the database schema definition.
+type changeset struct {
+	operations []Operation
+}
+
+// Add new operations to the changeset.
+func (c *changeset) Add(op ...Operation) {
+	c.operations = append(c.operations, op...)
+}
+
+// diff calculates the diff between the current database schema and the target state.
+// The changeset is not sorted -- the caller should resolve dependencies before applying the changes.
+func diff(got, want sqlschema.Database, opts ...diffOption) *changeset {
+	d := newDetector(got, want, opts...)
+	return d.detectChanges()
+}
+
+func (d *detector) detectChanges() *changeset {
+	currentTables := d.current.GetTables()
+	targetTables := d.target.GetTables()
+
+RenameCreate:
+	for wantName, wantTable := range targetTables.FromOldest() {
+
+		// A table with this name exists in the database. We assume that schema objects won't
+		// be renamed to an already existing name, nor do we support such cases.
+		// Simply check if the table definition has changed.
+		if haveTable, ok := currentTables.Get(wantName); ok {
+			d.detectColumnChanges(haveTable, wantTable, true)
+			d.detectConstraintChanges(haveTable, wantTable)
+			continue
+		}
+
+		// Find all renamed tables. We assume that renamed tables have the same signature.
+		for haveName, haveTable := range currentTables.FromOldest() {
+			if _, exists := targetTables.Get(haveName); !exists && d.canRename(haveTable, wantTable) {
+				d.changes.Add(&RenameTableOp{
+					TableName: haveTable.GetName(),
+					NewName:   wantName,
+				})
+				d.refMap.RenameTable(haveTable.GetName(), wantName)
+
+				// Find renamed columns, if any, and check if constraints (PK, UNIQUE) have been updated.
+				// We need not check wantTable any further.
+				d.detectColumnChanges(haveTable, wantTable, false)
+				d.detectConstraintChanges(haveTable, wantTable)
+				currentTables.Delete(haveName)
+				continue RenameCreate
+			}
+		}
+
+		// If wantTable does not exist in the database and was not renamed
+		// then we need to create this table in the database.
+		additional := wantTable.(*sqlschema.BunTable)
+		d.changes.Add(&CreateTableOp{
+			TableName: wantTable.GetName(),
+			Model:     additional.Model,
+		})
+	}
+
+	// Drop any remaining "current" tables which do not have a model.
+	for name, table := range currentTables.FromOldest() {
+		if _, keep := targetTables.Get(name); !keep {
+			d.changes.Add(&DropTableOp{
+				TableName: table.GetName(),
+			})
+		}
+	}
+
+	targetFKs := d.target.GetForeignKeys()
+	currentFKs := d.refMap.Deref()
+
+	for fk := range targetFKs {
+		if _, ok := currentFKs[fk]; !ok {
+			d.changes.Add(&AddForeignKeyOp{
+				ForeignKey:     fk,
+				ConstraintName: "", // leave empty to let each dialect apply their convention
+			})
+		}
+	}
+
+	for fk, name := range currentFKs {
+		if _, ok := targetFKs[fk]; !ok {
+			d.changes.Add(&DropForeignKeyOp{
+				ConstraintName: name,
+				ForeignKey:     fk,
+			})
+		}
+	}
+
+	return &d.changes
+}
+
+// detechColumnChanges finds renamed columns and, if checkType == true, columns with changed type.
+func (d *detector) detectColumnChanges(current, target sqlschema.Table, checkType bool) {
+	currentColumns := current.GetColumns()
+	targetColumns := target.GetColumns()
+
+ChangeRename:
+	for tName, tCol := range targetColumns.FromOldest() {
+
+		// This column exists in the database, so it hasn't been renamed, dropped, or added.
+		// Still, we should not delete(columns, thisColumn), because later we will need to
+		// check that we do not try to rename a column to an already a name that already exists.
+		if cCol, ok := currentColumns.Get(tName); ok {
+			if checkType && !d.equalColumns(cCol, tCol) {
+				d.changes.Add(&ChangeColumnTypeOp{
+					TableName: target.GetName(),
+					Column:    tName,
+					From:      cCol,
+					To:        d.makeTargetColDef(cCol, tCol),
+				})
+			}
+			continue
+		}
+
+		// Column tName does not exist in the database -- it's been either renamed or added.
+		// Find renamed columns first.
+		for cName, cCol := range currentColumns.FromOldest() {
+			// Cannot rename if a column with this name already exists or the types differ.
+			if _, exists := targetColumns.Get(cName); exists || !d.equalColumns(tCol, cCol) {
+				continue
+			}
+			d.changes.Add(&RenameColumnOp{
+				TableName: target.GetName(),
+				OldName:   cName,
+				NewName:   tName,
+			})
+			d.refMap.RenameColumn(target.GetName(), cName, tName)
+			currentColumns.Delete(cName) // no need to check this column again
+
+			// Update primary key definition to avoid superficially recreating the constraint.
+			current.GetPrimaryKey().Columns.Replace(cName, tName)
+
+			continue ChangeRename
+		}
+
+		d.changes.Add(&AddColumnOp{
+			TableName:  target.GetName(),
+			ColumnName: tName,
+			Column:     tCol,
+		})
+	}
+
+	// Drop columns which do not exist in the target schema and were not renamed.
+	for cName, cCol := range currentColumns.FromOldest() {
+		if _, keep := targetColumns.Get(cName); !keep {
+			d.changes.Add(&DropColumnOp{
+				TableName:  target.GetName(),
+				ColumnName: cName,
+				Column:     cCol,
+			})
+		}
+	}
+}
+
+func (d *detector) detectConstraintChanges(current, target sqlschema.Table) {
+Add:
+	for _, want := range target.GetUniqueConstraints() {
+		for _, got := range current.GetUniqueConstraints() {
+			if got.Equals(want) {
+				continue Add
+			}
+		}
+		d.changes.Add(&AddUniqueConstraintOp{
+			TableName: target.GetName(),
+			Unique:    want,
+		})
+	}
+
+Drop:
+	for _, got := range current.GetUniqueConstraints() {
+		for _, want := range target.GetUniqueConstraints() {
+			if got.Equals(want) {
+				continue Drop
+			}
+		}
+
+		d.changes.Add(&DropUniqueConstraintOp{
+			TableName: target.GetName(),
+			Unique:    got,
+		})
+	}
+
+	targetPK := target.GetPrimaryKey()
+	currentPK := current.GetPrimaryKey()
+
+	// Detect primary key changes
+	if targetPK == nil && currentPK == nil {
+		return
+	}
+	switch {
+	case targetPK == nil && currentPK != nil:
+		d.changes.Add(&DropPrimaryKeyOp{
+			TableName:  target.GetName(),
+			PrimaryKey: *currentPK,
+		})
+	case currentPK == nil && targetPK != nil:
+		d.changes.Add(&AddPrimaryKeyOp{
+			TableName:  target.GetName(),
+			PrimaryKey: *targetPK,
+		})
+	case targetPK.Columns != currentPK.Columns:
+		d.changes.Add(&ChangePrimaryKeyOp{
+			TableName: target.GetName(),
+			Old:       *currentPK,
+			New:       *targetPK,
+		})
+	}
+}
+
+func newDetector(got, want sqlschema.Database, opts ...diffOption) *detector {
+	cfg := &detectorConfig{
+		cmpType: func(c1, c2 sqlschema.Column) bool {
+			return c1.GetSQLType() == c2.GetSQLType() && c1.GetVarcharLen() == c2.GetVarcharLen()
+		},
+	}
+	for _, opt := range opts {
+		opt(cfg)
+	}
+
+	return &detector{
+		current: got,
+		target:  want,
+		refMap:  newRefMap(got.GetForeignKeys()),
+		cmpType: cfg.cmpType,
+	}
+}
+
+type diffOption func(*detectorConfig)
+
+func withCompareTypeFunc(f CompareTypeFunc) diffOption {
+	return func(cfg *detectorConfig) {
+		cfg.cmpType = f
+	}
+}
+
+// detectorConfig controls how differences in the model states are resolved.
+type detectorConfig struct {
+	cmpType CompareTypeFunc
+}
+
+// detector may modify the passed database schemas, so it isn't safe to re-use them.
+type detector struct {
+	// current state represents the existing database schema.
+	current sqlschema.Database
+
+	// target state represents the database schema defined in bun models.
+	target sqlschema.Database
+
+	changes changeset
+	refMap  refMap
+
+	// cmpType determines column type equivalence.
+	// Default is direct comparison with '==' operator, which is inaccurate
+	// due to the existence of dialect-specific type aliases. The caller
+	// should pass a concrete InspectorDialect.EquuivalentType for robust comparison.
+	cmpType CompareTypeFunc
+}
+
+// canRename checks if t1 can be renamed to t2.
+func (d detector) canRename(t1, t2 sqlschema.Table) bool {
+	return t1.GetSchema() == t2.GetSchema() && equalSignatures(t1, t2, d.equalColumns)
+}
+
+func (d detector) equalColumns(col1, col2 sqlschema.Column) bool {
+	return d.cmpType(col1, col2) &&
+		col1.GetDefaultValue() == col2.GetDefaultValue() &&
+		col1.GetIsNullable() == col2.GetIsNullable() &&
+		col1.GetIsAutoIncrement() == col2.GetIsAutoIncrement() &&
+		col1.GetIsIdentity() == col2.GetIsIdentity()
+}
+
+func (d detector) makeTargetColDef(current, target sqlschema.Column) sqlschema.Column {
+	// Avoid unneccessary type-change migrations if the types are equivalent.
+	if d.cmpType(current, target) {
+		target = &sqlschema.BaseColumn{
+			Name:            target.GetName(),
+			DefaultValue:    target.GetDefaultValue(),
+			IsNullable:      target.GetIsNullable(),
+			IsAutoIncrement: target.GetIsAutoIncrement(),
+			IsIdentity:      target.GetIsIdentity(),
+
+			SQLType:    current.GetSQLType(),
+			VarcharLen: current.GetVarcharLen(),
+		}
+	}
+	return target
+}
+
+type CompareTypeFunc func(sqlschema.Column, sqlschema.Column) bool
+
+// equalSignatures determines if two tables have the same "signature".
+func equalSignatures(t1, t2 sqlschema.Table, eq CompareTypeFunc) bool {
+	sig1 := newSignature(t1, eq)
+	sig2 := newSignature(t2, eq)
+	return sig1.Equals(sig2)
+}
+
+// signature is a set of column definitions, which allows "relation/name-agnostic" comparison between them;
+// meaning that two columns are considered equal if their types are the same.
+type signature struct {
+
+	// underlying stores the number of occurences for each unique column type.
+	// It helps to account for the fact that a table might have multiple columns that have the same type.
+	underlying map[sqlschema.BaseColumn]int
+
+	eq CompareTypeFunc
+}
+
+func newSignature(t sqlschema.Table, eq CompareTypeFunc) signature {
+	s := signature{
+		underlying: make(map[sqlschema.BaseColumn]int),
+		eq:         eq,
+	}
+	s.scan(t)
+	return s
+}
+
+// scan iterates over table's field and counts occurrences of each unique column definition.
+func (s *signature) scan(t sqlschema.Table) {
+	for _, icol := range t.GetColumns().FromOldest() {
+		scanCol := icol.(*sqlschema.BaseColumn)
+		// This is slightly more expensive than if the columns could be compared directly
+		// and we always did s.underlying[col]++, but we get type-equivalence in return.
+		col, count := s.getCount(*scanCol)
+		if count == 0 {
+			s.underlying[*scanCol] = 1
+		} else {
+			s.underlying[col]++
+		}
+	}
+}
+
+// getCount uses CompareTypeFunc to find a column with the same (equivalent) SQL type
+// and returns its count. Count 0 means there are no columns with of this type.
+func (s *signature) getCount(keyCol sqlschema.BaseColumn) (key sqlschema.BaseColumn, count int) {
+	for col, cnt := range s.underlying {
+		if s.eq(&col, &keyCol) {
+			return col, cnt
+		}
+	}
+	return keyCol, 0
+}
+
+// Equals returns true if 2 signatures share an identical set of columns.
+func (s *signature) Equals(other signature) bool {
+	if len(s.underlying) != len(other.underlying) {
+		return false
+	}
+	for col, count := range s.underlying {
+		if _, countOther := other.getCount(col); countOther != count {
+			return false
+		}
+	}
+	return true
+}
+
+// refMap is a utility for tracking superficial changes in foreign keys,
+// which do not require any modificiation in the database.
+// Modern SQL dialects automatically updated foreign key constraints whenever
+// a column or a table is renamed. Detector can use refMap to ignore any
+// differences in foreign keys which were caused by renamed column/table.
+type refMap map[*sqlschema.ForeignKey]string
+
+func newRefMap(fks map[sqlschema.ForeignKey]string) refMap {
+	rm := make(map[*sqlschema.ForeignKey]string)
+	for fk, name := range fks {
+		rm[&fk] = name
+	}
+	return rm
+}
+
+// RenameT updates table name in all foreign key definions which depend on it.
+func (rm refMap) RenameTable(tableName string, newName string) {
+	for fk := range rm {
+		switch tableName {
+		case fk.From.TableName:
+			fk.From.TableName = newName
+		case fk.To.TableName:
+			fk.To.TableName = newName
+		}
+	}
+}
+
+// RenameColumn updates column name in all foreign key definions which depend on it.
+func (rm refMap) RenameColumn(tableName string, column, newName string) {
+	for fk := range rm {
+		if tableName == fk.From.TableName {
+			fk.From.Column.Replace(column, newName)
+		}
+		if tableName == fk.To.TableName {
+			fk.To.Column.Replace(column, newName)
+		}
+	}
+}
+
+// Deref returns copies of ForeignKey values to a map.
+func (rm refMap) Deref() map[sqlschema.ForeignKey]string {
+	out := make(map[sqlschema.ForeignKey]string)
+	for fk, name := range rm {
+		out[*fk] = name
+	}
+	return out
+}