five/hbrdd/base.go

// Copyright (c) 2026 Charles KWON OhJun (charleskwonohjun@gmail.com)
// All rights reserved.

// BaseArea provides default implementations for the Area interface.
// Harbour equivalent: WAAREA (workarea.c) — ~25 real + ~76 stub methods.
// Concrete drivers (DBFArea, etc.) embed BaseArea and override as needed.
package hbrdd

import "five/hbrt"

// BaseArea is the base workarea with default flag management.
// Harbour: struct _AREA in hbapirdd.h
type BaseArea struct {
	driver    Driver
	alias     string
	fields    []FieldInfo
	fieldMap  map[string]int // field name → index (0-based)

	// Cursor state flags — Harbour: fBof, fEof, fFound, fTop, fBottom
	FBof   bool
	FEof   bool
	FFound bool
	FTop   bool
	FBottom bool

	// Filter
	filterExpr  string
	filterBlock func(*hbrt.Thread) bool

	// Relations
	relations []*Relation
}

// Relation holds a parent→child relationship.
type Relation struct {
	Child   Area
	KeyExpr func(*hbrt.Thread) hbrt.Value
	Scoped  bool
}

// --- BaseArea default implementations ---

func (a *BaseArea) Driver() Driver   { return a.driver }
func (a *BaseArea) Alias() string    { return a.alias }
func (a *BaseArea) BOF() bool        { return a.FBof }
func (a *BaseArea) EOF() bool        { return a.FEof }
func (a *BaseArea) Found() bool      { return a.FFound }
func (a *BaseArea) SetFound(b bool)  { a.FFound = b }
func (a *BaseArea) FieldCount() int  { return len(a.fields) }

func (a *BaseArea) GetFieldInfo(index int) FieldInfo {
	if index >= 0 && index < len(a.fields) {
		return a.fields[index]
	}
	return FieldInfo{}
}

// FieldIndex returns the 0-based field index by name, or -1 if not found.
func (a *BaseArea) FieldIndex(name string) int {
	if a.fieldMap == nil {
		return -1
	}
	if idx, ok := a.fieldMap[name]; ok {
		return idx
	}
	return -1
}

// InitFields sets up the field array and name→index map.
func (a *BaseArea) InitFields(fields []FieldInfo) {
	a.fields = fields
	a.fieldMap = make(map[string]int, len(fields))
	for i, f := range fields {
		a.fieldMap[f.Name] = i
	}
}

// Close provides the base close behavior (reset flags).
// Harbour: hb_waClose
func (a *BaseArea) Close() error {
	a.FBof = true
	a.FEof = true
	a.FFound = false
	a.fields = nil
	a.fieldMap = nil
	a.relations = nil
	return nil
}

// --- Filter support ---

func (a *BaseArea) SetFilter(expr string, block func(*hbrt.Thread) bool) error {
	a.filterExpr = expr
	a.filterBlock = block
	return nil
}

func (a *BaseArea) ClearFilter() error {
	a.filterExpr = ""
	a.filterBlock = nil
	return nil
}

func (a *BaseArea) HasFilter() bool {
	return a.filterBlock != nil
}

// --- Relation support ---

func (a *BaseArea) SetRelation(child Area, keyExpr func(*hbrt.Thread) hbrt.Value, scoped bool) error {
	a.relations = append(a.relations, &Relation{
		Child:   child,
		KeyExpr: keyExpr,
		Scoped:  scoped,
	})
	return nil
}

func (a *BaseArea) ClearRelation() error {
	a.relations = nil
	return nil
}