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

// Stack introspection: PROCNAME, PROCLINE, PROCFILE, ERRORLEVEL

package hbrtl

import (
	"five/hbrt"
	"os"
	"strconv"
	"strings"
	"time"
)

// Silence unused import warning
var _ = strconv.Itoa

// PROCNAME([nLevel]) → cFunctionName
func ProcName(t *hbrt.Thread) {
	nParams := t.ParamCount()
	t.Frame(nParams, 0)
	defer t.EndProc()

	level := 0
	if nParams >= 1 && !t.Local(1).IsNil() {
		level = t.Local(1).AsInt()
	}

	stack := t.DebugCallStack()
	if level >= 0 && level < len(stack) {
		t.RetString(stack[level].Function)
	} else {
		t.RetString("")
	}
}

// PROCLINE([nLevel]) → nLineNumber
func ProcLine(t *hbrt.Thread) {
	nParams := t.ParamCount()
	t.Frame(nParams, 0)
	defer t.EndProc()

	level := 0
	if nParams >= 1 && !t.Local(1).IsNil() {
		level = t.Local(1).AsInt()
	}

	stack := t.DebugCallStack()
	if level >= 0 && level < len(stack) {
		t.RetInt(int64(stack[level].Line))
	} else {
		t.RetInt(0)
	}
}

// PROCFILE([nLevel]) → cSourceFileName
func ProcFile(t *hbrt.Thread) {
	nParams := t.ParamCount()
	t.Frame(nParams, 0)
	defer t.EndProc()

	level := 0
	if nParams >= 1 && !t.Local(1).IsNil() {
		level = t.Local(1).AsInt()
	}

	stack := t.DebugCallStack()
	if level >= 0 && level < len(stack) {
		t.RetString(stack[level].Module)
	} else {
		t.RetString("")
	}
}

var exitLevel int

// ERRORLEVEL([nNewLevel]) → nOldLevel
func ErrorLevel(t *hbrt.Thread) {
	nParams := t.ParamCount()
	t.Frame(nParams, 0)
	defer t.EndProc()

	old := exitLevel
	if nParams >= 1 && !t.Local(1).IsNil() {
		exitLevel = t.Local(1).AsInt()
	}
	t.RetInt(int64(old))
}

// TONE(nFrequency [, nDuration]) → NIL
func Tone(t *hbrt.Thread) {
	nParams := t.ParamCount()
	t.Frame(nParams, 0)
	defer t.EndProc()
	// Terminal bell
	os.Stdout.Write([]byte{7})
	t.RetNil()
}

// CENTER(cString, nWidth [, cFill]) → cCentered (alias: PADC)
func Center(t *hbrt.Thread) {
	PadC(t)
}

// STRZERO already exists, HB_NTOS already exists

// HB_NTOS(nValue) → cString (no leading spaces) — already in missing.go

// FIELDPOS(cFieldName) → nPos
func FieldPos(t *hbrt.Thread) {
	t.Frame(1, 0)
	defer t.EndProcFast()
	fname := strings.ToUpper(t.Local(1).AsString())
	wam := getWA(t)
	if wam == nil {
		t.RetInt(0)
		return
	}
	area := wam.Current()
	if area == nil {
		t.RetInt(0)
		return
	}

	// Try DBFArea's built-in field position cache (O(1) hash lookup).
	// Falls back to linear scan for non-DBF areas (mem RDD, etc.).
	type fieldPosCacher interface {
		FieldPosCache(name string) int
	}
	if fpc, ok := area.(fieldPosCacher); ok {
		pos := fpc.FieldPosCache(fname)
		t.RetInt(int64(pos))
		return
	}

	// Fallback: linear scan
	for i := 0; i < area.FieldCount(); i++ {
		fi := area.GetFieldInfo(i)
		if strings.EqualFold(fi.Name, fname) {
			t.RetInt(int64(i + 1))
			return
		}
	}
	t.RetInt(0)
}

func eqFold(a, b string) bool {
	if len(a) != len(b) {
		return false
	}
	for i := 0; i < len(a); i++ {
		ca, cb := a[i], b[i]
		if ca >= 'a' && ca <= 'z' {
			ca -= 32
		}
		if cb >= 'a' && cb <= 'z' {
			cb -= 32
		}
		if ca != cb {
			return false
		}
	}
	return true
}

// FIELDBLOCK(nField) → bBlock — create block that reads field n
func FieldBlockFunc(t *hbrt.Thread) {
	t.Frame(1, 0)
	defer t.EndProc()
	nField := t.Local(1).AsInt()
	// Create a block that calls FieldGet(nField) on the current area
	blk := hbrt.MakeBlock(func(t2 *hbrt.Thread) {
		t2.Frame(0, 0)
		defer t2.EndProc()
		wam := getWA(t2)
		if wam != nil {
			if area := wam.Current(); area != nil {
				val, _ := area.GetValue(nField - 1) // 1-based to 0-based
				t2.PushValue(val)
				t2.RetValue()
				return
			}
		}
		t2.RetNil()
	}, 0)
	t.RetVal(blk)
}

// FIELDNAME(nField) → cName
func FieldNameFunc(t *hbrt.Thread) {
	t.Frame(1, 0)
	defer t.EndProc()
	nField := t.Local(1).AsInt()
	wam := getWA(t)
	if wam != nil {
		if area := wam.Current(); area != nil {
			if nField >= 1 && nField <= area.FieldCount() {
				fi := area.GetFieldInfo(nField - 1)
				t.RetString(fi.Name)
				return
			}
		}
	}
	t.RetString("")
}

// AFIELDS(@aNames [, @aTypes, @aWidths, @aDecs]) → nFieldCount
func AFields(t *hbrt.Thread) {
	nParams := t.ParamCount()
	t.Frame(nParams, 0)
	defer t.EndProc()

	wam := getWA(t)
	if wam == nil {
		t.RetInt(0)
		return
	}
	area := wam.Current()
	if area == nil {
		t.RetInt(0)
		return
	}
	nFields := area.FieldCount()
	t.RetInt(int64(nFields))
}

// DBSTRUCT() → aStruct (array of {name, type, len, dec})
func DbStruct(t *hbrt.Thread) {
	t.Frame(0, 0)
	defer t.EndProc()

	wam := getWA(t)
	if wam == nil {
		t.RetVal(hbrt.MakeArray(0))
		return
	}
	area := wam.Current()
	if area == nil {
		t.RetVal(hbrt.MakeArray(0))
		return
	}
	nFields := area.FieldCount()
	items := make([]hbrt.Value, nFields)
	for i := 0; i < nFields; i++ {
		fi := area.GetFieldInfo(i)
		// 5-element row: name / type / len / dec / flags. Harbour
		// dbStruct() is 4-element; the extra flags byte preserves
		// FieldFlagNullable (and future system/binary/autoinc bits)
		// across ALTER-TABLE table rebuilds so callers that feed
		// dbStruct output back into dbCreate don't silently drop
		// nullability. Four-element callers still index [1..4] as
		// before.
		row := []hbrt.Value{
			hbrt.MakeString(fi.Name),
			hbrt.MakeString(string(fi.Type)),
			hbrt.MakeInt(int(fi.Len)),
			hbrt.MakeInt(int(fi.Dec)),
			hbrt.MakeInt(int(fi.Flags)),
		}
		items[i] = hbrt.MakeArrayFrom(row)
	}
	t.RetVal(hbrt.MakeArrayFrom(items))
}

// HB_DATETIME([nYear, nMonth, nDay [, nHour [, nMin [, nSec [, nMsec]]]]]) → tTimestamp
func HbDatetime(t *hbrt.Thread) {
	nParams := t.ParamCount()
	t.Frame(nParams, 0)
	defer t.EndProc()

	if nParams == 0 {
		// No args: current date+time
		now := time.Now()
		y, m, d := now.Date()
		julian := dateToJulian(y, int(m), d)
		ms := int32(now.Hour()*3600000 + now.Minute()*60000 + now.Second()*1000 + now.Nanosecond()/1000000)
		t.RetVal(hbrt.MakeTimestamp(julian, ms))
		return
	}

	// With args: construct from components
	y := 0; m := 1; d := 1; hh := 0; mm := 0; ss := 0; ms := 0
	if nParams >= 1 { y = t.Local(1).AsInt() }
	if nParams >= 2 { m = t.Local(2).AsInt() }
	if nParams >= 3 { d = t.Local(3).AsInt() }
	if nParams >= 4 { hh = t.Local(4).AsInt() }
	if nParams >= 5 { mm = t.Local(5).AsInt() }
	if nParams >= 6 { ss = t.Local(6).AsInt() }
	if nParams >= 7 { ms = t.Local(7).AsInt() }

	julian := dateToJulian(y, m, d)
	timeMs := int32(hh*3600000 + mm*60000 + ss*1000 + ms)
	t.RetVal(hbrt.MakeTimestamp(julian, timeMs))
}