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 {
	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{
			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{
		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
}