plan

type Assemble struct {
	Entity  string   `json:"entity"`
	Alias   string   `json:"alias"`
	Columns []OutCol `json:"columns"`
	// AESVersion is the position, among Columns, of the column that holds the key version when the node reads
	// an AES column. If it is a selected column, it is that column as is; otherwise it is a hidden column.
	AESVersion *int     `json:"aes_version,omitempty"`
	Children   []*Child `json:"children,omitempty"`
	Key        []KeyRef `json:"key"`
}

type BindSlot struct {
	From      string `json:"from"`
	Param     int    `json:"param"`
	Transform string `json:"transform,omitempty"`
	Name      string `json:"name,omitempty"`
	Step      int    `json:"step,omitempty"`
	Column    string `json:"column,omitempty"`
	// HostStyles: style stages the dialect leaves to the executor for this
	// value (aes/hex/ip on PostgreSQL/SQLite): the executor applies them to
	// the bound value before sending it (write order). Empty on MySQL.
	HostStyles []string `json:"host_styles,omitempty"`
	// ColType is the dbspec type of the value that a placeholder takes. A value compared with, or
	// assigned to, a column has that column's type (a value passed through a host style is stored in the column,
	// so it is the same). The value a SQL-side style function takes is the type of that function's input;
	// a value compared with a function is the type of its result; a secret is text; config is the type of the
	// column that stores the value; now is datetime; and audit is the type of the audit column. A parent
	// slot carries KeyTypes instead of ColType. A slot with no type does not exist.
	ColType string `json:"col_type,omitempty"`
	// KeyTypes are the dbspec types of the key values that a parent slot expands, in key column order.
	KeyTypes  []string `json:"key_types,omitempty"`
	Precision int      `json:"precision,omitempty"`
	Scale     int      `json:"scale,omitempty"`
	// Length is the n of a varchar(n) slot: a value has at most n characters.
	Length int `json:"length,omitempty"`
	// NotNull marks a param slot that assigns the non-null column Column (set, rows,
	// on_duplicate, the restore set): a NULL value is CODEC_ENCODE before any statement.
	NotNull bool `json:"not_null,omitempty"`
}

type Child struct {
	Rel        string   `json:"rel"`
	Kind       string   `json:"kind"` // join | one | many
	Step       int      `json:"step,omitempty"`
	ParentKeys []KeyRef `json:"parent_keys,omitempty"`
	ChildKeys  []KeyRef `json:"child_keys,omitempty"`
	Key        []KeyRef `json:"key,omitempty"`
	Flatten    bool     `json:"flatten,omitempty"`
	// Cascade: the related rows belong to this row (their FK points here) and
	// no_cascade_delete was not set — deleteCascade removes them first.
	Cascade  bool      `json:"cascade,omitempty"`
	Assemble *Assemble `json:"assemble,omitempty"`
}

type IfParent struct {
	Column string `json:"column"`
	Index  int    `json:"index"`
	Param  int    `json:"param"`
}

type KeyRef struct {
	Column string `json:"column"`
	Index  int    `json:"index"`
}

type OutCol struct {
	Index  int      `json:"index"`
	Name   string   `json:"name"`             // output name (column or alias)
	Column string   `json:"column,omitempty"` // source column, "" for expr
	Type   string   `json:"type"`
	Styles []string `json:"styles,omitempty"` // remaining client-side decode stages
	Hidden bool     `json:"hidden,omitempty"` // selected for writing only (the AES key version): left out of array/JSON forms
}

type ParentRef struct {
	Step     int       `json:"step"`
	Keys     []KeyRef  `json:"keys"`
	IfParent *IfParent `json:"if_parent,omitempty"`
}

type Plan struct {
	ManifestHash string `json:"manifest_hash"`
	Kind         string `json:"kind"`
	Steps        []Step `json:"steps"`
}

type Step struct {
	ID   int    `json:"id"`
	Role string `json:"role"` // main | count | relation
	SQL  string `json:"sql"`
	// Tables are the tables that the statement names: physical table names, sorted and deduplicated.
	Tables    []string   `json:"tables"`
	Lock      string     `json:"lock,omitempty"` // adapter lock mode for a root row select
	BindSlots []BindSlot `json:"bind_slots"`
	Assemble  *Assemble  `json:"assemble,omitempty"`
	Parent    *ParentRef `json:"parent,omitempty"` // relation steps: where the IN values come from
}