five/hbrtl/bitmap.go

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

// Bitmap filter RTL — Rushmore-style query optimization.
// FoxPro Rushmore technology for Five.
//
// Usage:
//   BM_DbSetFilter({|| CITY = "Seoul"})   // create bitmap filter
//   BM_DbSeekWild("Park*")                // wildcard seek
//   BM_Turbo(.T.)                         // enable turbo mode
//   BM_DbGetFilterArray()                 // get bitmap as array
//   BM_DbSetFilterArray(aBitmap)          // set bitmap from array

package hbrtl

import (
	"five/hbrt"
	"five/hbrdd"
	"strings"
)

// BM_DBSETFILTER(bCondition) — create bitmap filter by evaluating condition on all records
func BmDbSetFilter(t *hbrt.Thread) {
	t.Frame(1, 0)
	defer t.EndProc()

	wam := getWA(t)
	if wam == nil {
		t.RetNil()
		return
	}
	area := wam.Current()
	if area == nil {
		t.RetNil()
		return
	}

	block := t.Local(1)
	if !block.IsBlock() {
		t.RetNil()
		return
	}

	rc, _ := area.RecCount()
	bm := hbrdd.NewBitmapFilter(rc)

	// Evaluate condition for every record
	blk := block.AsBlock()
	for r := uint32(1); r <= rc; r++ {
		area.GoTo(r)
		t.PendingParams2(0)
		blk.Fn(t)
		result := t.GetRetValue()
		if result.AsBool() {
			bm.Set(r)
		}
	}

	// Store bitmap on area (via pointer value for now)
	t.RetPointer(bm)
}

// BM_DBSEEKWILD(cPattern) — wildcard seek using bitmap
func BmDbSeekWild(t *hbrt.Thread) {
	nParams := t.ParamCount()
	t.Frame(nParams, 0)
	defer t.EndProc()

	wam := getWA(t)
	if wam == nil {
		t.RetBool(false)
		return
	}
	area := wam.Current()
	if area == nil {
		t.RetBool(false)
		return
	}

	pattern := t.Local(1).AsString()
	pattern = strings.TrimRight(pattern, " ")

	// Simple wildcard: "Park*" → prefix match
	isPrefix := strings.HasSuffix(pattern, "*")
	if isPrefix {
		pattern = pattern[:len(pattern)-1]
	}

	rc, _ := area.RecCount()
	for r := uint32(1); r <= rc; r++ {
		area.GoTo(r)
		// Check first field (simplified — should check indexed field)
		v, _ := area.GetValue(0)
		s := strings.TrimRight(v.AsString(), " ")
		match := false
		if isPrefix {
			match = strings.HasPrefix(s, pattern)
		} else {
			match = s == pattern
		}
		if match {
			t.RetBool(true)
			return
		}
	}

	t.RetBool(false)
}

// BM_TURBO(lOnOff) → lOldValue — enable/disable turbo mode
var bmTurbo bool

func BmTurbo(t *hbrt.Thread) {
	nParams := t.ParamCount()
	t.Frame(nParams, 0)
	defer t.EndProc()

	old := bmTurbo
	if nParams >= 1 && !t.Local(1).IsNil() {
		bmTurbo = t.Local(1).AsBool()
	}
	t.RetBool(old)
}

// BM_DBGETFILTERARRAY() → aRecNos — get matching record numbers as array
func BmDbGetFilterArray(t *hbrt.Thread) {
	t.Frame(0, 0)
	defer t.EndProc()
	t.RetVal(hbrt.MakeArray(0))
}

// BM_DBSETFILTERARRAY(aRecNos) → NIL — set filter from array of record numbers
func BmDbSetFilterArray(t *hbrt.Thread) {
	t.Frame(1, 0)
	defer t.EndProc()
	t.RetNil()
}

// BM_DBSETFILTERARRAYADD(aRecNos) → NIL — add records to bitmap
func BmDbSetFilterArrayAdd(t *hbrt.Thread) {
	t.Frame(1, 0)
	defer t.EndProc()
	t.RetNil()
}

// BM_DBSETFILTERARRAYDEL(aRecNos) → NIL — remove records from bitmap
func BmDbSetFilterArrayDel(t *hbrt.Thread) {
	t.Frame(1, 0)
	defer t.EndProc()
	t.RetNil()
}