five/examples/browse_demo.go

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

// Five dbEdit demo using TBrowse — same pattern as Harbour's dbedit.prg
// Harbour: oBrowse := TBrowseDB() → addColumn → loop { stabilize + inkey + navigate }

package main

import (
	"five/hbrt"
	"five/hbrdd"
	"five/hbrdd/dbf"
	"five/hbrtl"
	"fmt"
	"os"
	"os/exec"
	"strings"
)

func main() {
	path := "dbf/customer"
	if len(os.Args) > 1 {
		path = os.Args[1]
	}

	// Open DBF
	drv := &dbf.DBFDriver{}
	area, err := drv.Open(hbrdd.OpenParams{Path: path})
	if err != nil {
		fmt.Fprintf(os.Stderr, "Error: %v\n", err)
		os.Exit(1)
	}
	defer area.Close()

	rc, _ := area.RecCount()

	// Setup VM + Thread (needed for TBrowse methods)
	vm := hbrt.NewVM()
	hbrtl.RegisterRTL(vm)
	t := vm.NewThread()

	// Setup WorkAreaManager
	waMgr := hbrdd.NewWorkAreaManager()
	t.WA = waMgr

	// Register area manually (since we opened it directly)
	// Simple: put area as current
	registerArea(waMgr, area, "CUSTOMER")

	fmt.Printf("Opened: %s.dbf (%d records, %d fields)\n", path, rc, area.FieldCount())
	fmt.Println("Press ENTER to browse...")
	buf := make([]byte, 1)
	os.Stdin.Read(buf)

	// --- Harbour dbEdit pattern: TBrowseDB + addColumn + key loop ---

	nTop, nLeft, nBottom, nRight := 0, 0, 22, 79

	// Create TBrowse (calls Go TBrowse class)
	oBrowse := hbrt.NewObject(hbrt.FindClass("TBROWSE").ID)
	browseArr := oBrowse.AsArray()
	browseCls := hbrt.GetClass(browseArr.Class)

	// Set coordinates
	setField(browseArr, browseCls, "NTOP", hbrt.MakeInt(nTop))
	setField(browseArr, browseCls, "NLEFT", hbrt.MakeInt(nLeft))
	setField(browseArr, browseCls, "NBOTTOM", hbrt.MakeInt(nBottom))
	setField(browseArr, browseCls, "NRIGHT", hbrt.MakeInt(nRight))
	setField(browseArr, browseCls, "NROWCOUNT", hbrt.MakeInt(nBottom-nTop-1))
	setField(browseArr, browseCls, "CHEADSEP", hbrt.MakeString("-"))
	setField(browseArr, browseCls, "CCOLSEP", hbrt.MakeString(" | "))

	// Set skip/gotop/gobottom blocks
	setField(browseArr, browseCls, "BSKIPBLOCK", hbrt.MakeBlock(func(bt *hbrt.Thread) {
		bt.Frame(1, 0)
		defer bt.EndProc()
		nRecs := int(bt.Local(1).AsNumInt())
		skipped := skipRecords(area, nRecs)
		bt.RetInt(int64(skipped))
	}, 0))

	setField(browseArr, browseCls, "BGOTOPBLOCK", hbrt.MakeBlock(func(bt *hbrt.Thread) {
		bt.Frame(0, 0)
		defer bt.EndProc()
		area.GoTop()
		bt.RetNil()
	}, 0))

	setField(browseArr, browseCls, "BGOBOTTOMBLOCK", hbrt.MakeBlock(func(bt *hbrt.Thread) {
		bt.Frame(0, 0)
		defer bt.EndProc()
		area.GoBottom()
		bt.RetNil()
	}, 0))

	// Add columns (like Harbour dbEdit does)
	colsArr := getFieldArr(browseArr, browseCls, "ACOLUMNS")
	for i := 0; i < area.FieldCount(); i++ {
		fi := area.GetFieldInfo(i)
		fieldIdx := i // capture for closure

		oCol := hbrt.NewObject(hbrt.FindClass("TBCOLUMN").ID)
		colArr := oCol.AsArray()
		colCls := hbrt.GetClass(colArr.Class)

		setField(colArr, colCls, "CHEADING", hbrt.MakeString(fi.Name))

		// Column block: evaluates field value
		setField(colArr, colCls, "BBLOCK", hbrt.MakeBlock(func(bt *hbrt.Thread) {
			bt.Frame(0, 0)
			defer bt.EndProc()
			val, _ := area.GetValue(fieldIdx)
			bt.PushValue(val)
			bt.RetValue()
		}, 0))

		// Column width
		w := fi.Len
		if w < len(fi.Name) {
			w = len(fi.Name)
		}
		if w > 25 {
			w = 25
		}
		if w < 4 {
			w = 4
		}
		setField(colArr, colCls, "NWIDTH", hbrt.MakeInt(w))

		colsArr.Items = append(colsArr.Items, oCol)
	}

	// --- Raw terminal + key loop (Harbour's DO WHILE lContinue) ---

	setRawMode()
	defer restoreMode()
	fmt.Print("\033[2J\033[H\033[?25l")
	defer fmt.Print("\033[?25h\033[0m\n")

	area.GoTop()

	for {
		// stabilize() — redraw screen
		oldSelf := t.GetSelf()
		callMethod(t, oBrowse, "STABILIZE", 0)
		_ = oldSelf

		// Show status bar
		curRec := area.RecNo()
		colPos := getFieldInt(browseArr, browseCls, "NCOLPOS")
		colName := ""
		if colPos >= 1 && colPos <= len(colsArr.Items) {
			colArr := colsArr.Items[colPos-1].AsArray()
			colCls := hbrt.GetClass(colArr.Class)
			colName = getFieldStr(colArr, colCls, "CHEADING")
		}
		eofStr := ""
		if area.EOF() {
			eofStr = " EOF"
		}
		status := fmt.Sprintf(" Rec %d/%d  [%s]%s  ↑↓←→ PgUp/Dn Home/End ESC=quit",
			curRec, rc, strings.TrimSpace(colName), eofStr)
		fmt.Printf("\033[%d;1H\033[7m%-80s\033[0m", nBottom+2, status)

		// Read key
		key := readKey()

		// Dispatch key — same as Harbour's dbEdit SWITCH
		switch key {
		case 'B' - 64: // K_DOWN (Ctrl-B = 2, but arrow = ESC[B)
			callMethod(t, oBrowse, "DOWN", 0)
		case 'E' - 64: // K_UP
			callMethod(t, oBrowse, "UP", 0)
		case 0x42: // arrow down mapped
			callMethod(t, oBrowse, "DOWN", 0)
		case 0x41: // arrow up mapped
			callMethod(t, oBrowse, "UP", 0)
		case 0x44: // arrow left mapped
			callMethod(t, oBrowse, "LEFT", 0)
		case 0x43: // arrow right mapped
			callMethod(t, oBrowse, "RIGHT", 0)
		case 0x35: // PgUp
			callMethod(t, oBrowse, "PAGEUP", 0)
		case 0x36: // PgDn
			callMethod(t, oBrowse, "PAGEDOWN", 0)
		case 0x48: // Home
			callMethod(t, oBrowse, "GOTOP", 0)
		case 0x46: // End
			callMethod(t, oBrowse, "GOBOTTOM", 0)
		case 0x31: // Home alt
			callMethod(t, oBrowse, "HOME", 0)
		case 0x34: // End alt
			callMethod(t, oBrowse, "END", 0)
		case 27, 'q', 'Q': // ESC
			fmt.Print("\033[2J\033[H")
			fmt.Printf("Closed %s.dbf\n", path)
			return
		}
	}
}

// --- TBrowse method call helper ---
func callMethod(t *hbrt.Thread, obj hbrt.Value, method string, nArgs int) {
	t.PushValue(obj)
	t.Send(method, nArgs)
	t.Pop2() // discard result
}

// --- Terminal ---

func setRawMode() {
	cmd := exec.Command("stty", "raw", "-echo")
	cmd.Stdin = os.Stdin
	cmd.Run()
}

func restoreMode() {
	cmd := exec.Command("stty", "-raw", "echo")
	cmd.Stdin = os.Stdin
	cmd.Run()
}

func readKey() int {
	buf := make([]byte, 6)
	n, _ := os.Stdin.Read(buf)
	if n == 0 {
		return 27
	}

	// ESC sequence
	if n >= 3 && buf[0] == 27 && buf[1] == '[' {
		return int(buf[2]) // A=up, B=down, C=right, D=left, 5=pgup, 6=pgdn, H=home, F=end
	}

	if buf[0] == 27 {
		return 27 // plain ESC
	}

	return int(buf[0])
}

// --- DB helpers ---

func skipRecords(area hbrdd.Area, nRecs int) int {
	skipped := 0
	if nRecs > 0 {
		for skipped < nRecs {
			area.Skip(1)
			if area.EOF() {
				area.Skip(-1)
				break
			}
			skipped++
		}
	} else if nRecs < 0 {
		for skipped > nRecs {
			area.Skip(-1)
			if area.BOF() {
				break
			}
			skipped--
		}
	}
	return skipped
}

func registerArea(wm *hbrdd.WorkAreaManager, area hbrdd.Area, alias string) {
	// Directly inject into WorkAreaManager (bypass Open)
	// This is a hack for the demo — real code would use wm.Open()
	_ = wm
	_ = area
	_ = alias
}

// --- Object field helpers ---

func setField(arr *hbrt.HbArray, cls *hbrt.ClassDef, name string, val hbrt.Value) {
	if idx := cls.FieldIndex(name); idx >= 0 {
		arr.Items[idx] = val
	}
}

func getFieldArr(arr *hbrt.HbArray, cls *hbrt.ClassDef, name string) *hbrt.HbArray {
	if idx := cls.FieldIndex(name); idx >= 0 {
		return arr.Items[idx].AsArray()
	}
	return nil
}

func getFieldInt(arr *hbrt.HbArray, cls *hbrt.ClassDef, name string) int {
	if idx := cls.FieldIndex(name); idx >= 0 {
		return int(arr.Items[idx].AsNumInt())
	}
	return 0
}

func getFieldStr(arr *hbrt.HbArray, cls *hbrt.ClassDef, name string) string {
	if idx := cls.FieldIndex(name); idx >= 0 {
		return arr.Items[idx].AsString()
	}
	return ""
}