package bdb

// ToManyRelationship describes a relationship between two tables where the
// local table has no id, and the foreign table has an id that matches a column
// in the local table.
type ToManyRelationship struct {
	Table    string
	Column   string
	Nullable bool
	Unique   bool

	ForeignTable          string
	ForeignColumn         string
	ForeignColumnNullable bool
	ForeignColumnUnique   bool

	ToJoinTable bool
	JoinTable   string

	JoinLocalColumn         string
	JoinLocalColumnNullable bool
	JoinLocalColumnUnique   bool

	JoinForeignColumn         string
	JoinForeignColumnNullable bool
	JoinForeignColumnUnique   bool
}

// ToManyRelationships relationship lookups
// Input should be the sql name of a table like: videos
func ToManyRelationships(table string, tables []Table) []ToManyRelationship {
	localTable := GetTable(tables, table)

	return toManyRelationships(localTable, tables)
}

func toManyRelationships(table Table, tables []Table) []ToManyRelationship {
	var relationships []ToManyRelationship

	for _, t := range tables {
		if t.Name == table.Name {
			continue
		}

		for _, f := range t.FKeys {
			if f.ForeignTable != table.Name {
				continue
			}

			relationships = append(relationships, buildRelationship(table, f, t, tables))
		}
	}

	return relationships
}

func buildRelationship(localTable Table, foreignKey ForeignKey, foreignTable Table, tables []Table) ToManyRelationship {
	if !foreignTable.IsJoinTable {
		col := localTable.GetColumn(foreignKey.ForeignColumn)
		return ToManyRelationship{
			Table:                 foreignKey.Table,
			Column:                foreignKey.ForeignColumn,
			Nullable:              col.Nullable,
			Unique:                col.Unique,
			ForeignTable:          foreignTable.Name,
			ForeignColumn:         foreignKey.Column,
			ForeignColumnNullable: foreignKey.Nullable,
			ForeignColumnUnique:   foreignKey.Unique,
			ToJoinTable:           false,
		}
	}

	col := foreignTable.GetColumn(foreignKey.Column)
	relationship := ToManyRelationship{
		Table:       foreignKey.Table,
		Column:      foreignKey.ForeignColumn,
		Nullable:    col.Nullable,
		Unique:      col.Unique,
		ToJoinTable: true,
		JoinTable:   foreignTable.Name,
	}

	for _, fk := range foreignTable.FKeys {
		if fk.ForeignTable != localTable.Name {
			relationship.JoinForeignColumn = fk.Column
			relationship.JoinForeignColumnNullable = fk.Nullable
			relationship.JoinForeignColumnUnique = fk.Unique

			foreignTable := GetTable(tables, fk.ForeignTable)
			foreignCol := foreignTable.GetColumn(fk.ForeignColumn)
			relationship.ForeignTable = fk.ForeignTable
			relationship.ForeignColumn = fk.ForeignColumn
			relationship.ForeignColumnNullable = foreignCol.Nullable
			relationship.ForeignColumnUnique = foreignCol.Unique
		} else {
			relationship.JoinLocalColumn = fk.Column
			relationship.JoinLocalColumnNullable = fk.Nullable
			relationship.JoinLocalColumnUnique = fk.Unique
		}
	}

	return relationship
}