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

// xBase command code generation for Five.
// Generates Go code that calls hbrdd WorkAreaManager methods.
package gengo

import (
	"five/compiler/ast"
	"five/compiler/token"
	"fmt"
	"strings"
)

func (g *Generator) emitUseCmd(s *ast.UseCmd, locals localMap) {
	if s.File == nil {
		// USE without args = close current
		g.writeln("{")
		g.indent++
		g.writeln("wa := t.WA.(*hbrdd.WorkAreaManager)")
		g.writeln("wa.Close()")
		g.indent--
		g.writeln("}")
		return
	}

	g.writeln("{")
	g.indent++
	g.writeln("wa := t.WA.(*hbrdd.WorkAreaManager)")
	g.emitExpr(s.File)
	g.writeln("_path := t.Pop2().AsString()")

	via := "DBFNTX" // default
	if s.Via != "" {
		via = s.Via
	}
	alias := s.Alias

	g.writeln(fmt.Sprintf("_, _err := wa.Open(%q, _path, %q, false, false)", via, alias))
	g.writeln("if _err != nil { panic(_err) }")
	g.indent--
	g.writeln("}")
}

func (g *Generator) emitGoCmd(s *ast.GoCmd) {
	g.writeln("{")
	g.indent++
	g.writeln("wa := t.WA.(*hbrdd.WorkAreaManager)")
	g.writeln("if area := wa.Current(); area != nil {")
	g.indent++

	switch s.Direction {
	case "TOP":
		g.writeln("area.GoTop()")
	case "BOTTOM":
		g.writeln("area.GoBottom()")
	default:
		if s.RecNo != nil {
			g.emitExpr(s.RecNo)
			g.writeln("area.GoTo(uint32(t.Pop2().AsNumInt()))")
		}
	}

	g.indent--
	g.writeln("}")
	g.indent--
	g.writeln("}")
}

func (g *Generator) emitSkipCmd(s *ast.SkipCmd, locals localMap) {
	g.writeln("{")
	g.indent++
	g.writeln("wa := t.WA.(*hbrdd.WorkAreaManager)")
	g.writeln("if area := wa.Current(); area != nil {")
	g.indent++

	if s.Count != nil {
		g.emitExpr(s.Count)
		g.writeln("area.Skip(t.Pop2().AsNumInt())")
	} else {
		g.writeln("area.Skip(1)")
	}

	g.indent--
	g.writeln("}")
	g.indent--
	g.writeln("}")
}

func (g *Generator) emitSeekCmd(s *ast.SeekCmd, locals localMap) {
	g.writeln("{")
	g.indent++
	g.writeln("wa := t.WA.(*hbrdd.WorkAreaManager)")
	g.writeln("if area := wa.Current(); area != nil {")
	g.indent++

	g.emitExpr(s.Key)
	g.writeln("_key := t.Pop2()")
	g.writeln("if _idx, ok := area.(hbrdd.Indexer); ok {")
	g.indent++
	g.writeln(fmt.Sprintf("_found, _ := _idx.Seek(_key, %v, false)", s.SoftSeek))
	g.writeln("_ = _found")
	g.indent--
	g.writeln("}")

	g.indent--
	g.writeln("}")
	g.indent--
	g.writeln("}")
}

func (g *Generator) emitReplaceCmd(s *ast.ReplaceCmd, locals localMap) {
	g.writeln("{")
	g.indent++
	g.writeln("wa := t.WA.(*hbrdd.WorkAreaManager)")
	g.writeln("if area := wa.Current(); area != nil {")
	g.indent++

	for _, rf := range s.Fields {
		// Get field name
		if ident, ok := rf.Field.(*ast.IdentExpr); ok {
			g.writeln(fmt.Sprintf("if _fi := area.(*dbf.DBFArea).FieldIndex(%q); _fi >= 0 {", ident.Name))
			g.indent++
			g.emitExpr(rf.Value)
			g.writeln(fmt.Sprintf("area.PutValue(_fi, t.Pop2())"))
			g.indent--
			g.writeln("}")
		}
	}
	g.writeln("area.Flush()")

	g.indent--
	g.writeln("}")
	g.indent--
	g.writeln("}")
}

// --- @ SAY / GET / READ commands ---

func (g *Generator) emitAtSayCmd(s *ast.AtSayCmd) {
	// DevPos(row, col)
	g.writeln(fmt.Sprintf("t.PushSymbol(t.VM().FindSymbol(\"DEVPOS\"))"))
	g.writeln("t.PushNil()")
	g.emitExpr(s.Row)
	g.emitExpr(s.Col)
	g.writeln("t.Do(2)")

	if s.Picture != nil {
		// DevOutPict(expr, pic)
		g.writeln(fmt.Sprintf("t.PushSymbol(t.VM().FindSymbol(\"DEVOUTPICT\"))"))
		g.writeln("t.PushNil()")
		g.emitExpr(s.SayExpr)
		g.emitExpr(s.Picture)
		g.writeln("t.Do(2)")
	} else {
		// DevOut(expr)
		g.writeln(fmt.Sprintf("t.PushSymbol(t.VM().FindSymbol(\"DEVOUT\"))"))
		g.writeln("t.PushNil()")
		g.emitExpr(s.SayExpr)
		g.writeln("t.Do(1)")
	}
}

func (g *Generator) emitAtGetCmd(s *ast.AtGetCmd, locals localMap) {
	// AAdd(GetList, GetNew(row, col, {|_1| IIF(_1==NIL, var, var:=_1)}, "varname" [, pic] [, {valid}] [, {when}]))
	g.writeln(fmt.Sprintf("t.PushSymbol(t.VM().FindSymbol(\"AADD\"))"))
	g.writeln("t.PushNil()")

	// Push GetList variable
	g.emitIdentByName("GetList", locals)

	// GetNew(row, col, block, name, ...)
	g.writeln(fmt.Sprintf("t.PushSymbol(t.VM().FindSymbol(\"GETNEW\"))"))
	g.writeln("t.PushNil()")
	g.emitExpr(s.Row)
	g.emitExpr(s.Col)

	// GET/SET block: {|_1| IIF(_1 == NIL, var, var := _1)}
	g.emitGetSetBlock(s.Var, s.VarName, locals)

	// Variable name as string
	g.writeln(fmt.Sprintf("t.PushString(%q)", s.VarName))

	nArgs := 4
	if s.Picture != nil {
		g.emitExpr(s.Picture)
		nArgs++
	}
	if s.Valid != nil {
		if s.Picture == nil {
			g.writeln("t.PushNil()") // placeholder for pic
			nArgs++
		}
		g.emitExpr(s.Valid)
		nArgs++
	}
	if s.When != nil {
		if s.Picture == nil && s.Valid == nil {
			g.writeln("t.PushNil()") // placeholder for pic
			g.writeln("t.PushNil()") // placeholder for valid
			nArgs += 2
		} else if s.Valid == nil {
			g.writeln("t.PushNil()") // placeholder for valid
			nArgs++
		}
		g.emitExpr(s.When)
		nArgs++
	}

	g.writeln(fmt.Sprintf("t.Function(%d)", nArgs))

	// AAdd(GetList, getObj) — 2 args
	g.writeln("t.Do(2)")

	// ATail(GetList):Display()
	g.writeln(fmt.Sprintf("t.PushSymbol(t.VM().FindSymbol(\"ATAIL\"))"))
	g.writeln("t.PushNil()")
	g.emitIdentByName("GetList", locals)
	g.writeln("t.Function(1)")
	g.writeln(fmt.Sprintf("t.Send(\"DISPLAY\", 0)"))
	g.writeln("t.Pop() // discard Display result")
}

func (g *Generator) emitAtSayGetCmd(s *ast.AtSayGetCmd, locals localMap) {
	// First: @ row, col SAY expr
	g.emitAtSayCmd(&ast.AtSayCmd{AtPos: s.AtPos, Row: s.Row, Col: s.Col, SayExpr: s.SayExpr})

	// Then: @ Row(), Col()+1 GET var ...
	g.emitAtGetCmd(&ast.AtGetCmd{
		AtPos:   s.AtPos,
		Row:     &ast.CallExpr{Func: &ast.IdentExpr{Name: "Row"}, Args: nil},
		Col:     &ast.BinaryExpr{Left: &ast.CallExpr{Func: &ast.IdentExpr{Name: "Col"}, Args: nil}, Op: token.PLUS, Right: &ast.LiteralExpr{Kind: token.INT, Value: "1"}}, // Col()+1
		Var:     s.Var,
		VarName: s.VarName,
		Picture: s.Picture,
		Valid:   s.Valid,
		When:    s.When,
	}, locals)
}

func (g *Generator) emitReadCmd(s *ast.ReadCmd, locals localMap) {
	// ReadModal(GetList)
	g.writeln(fmt.Sprintf("t.PushSymbol(t.VM().FindSymbol(\"READMODAL\"))"))
	g.writeln("t.PushNil()")
	g.emitIdentByName("GetList", locals)
	g.writeln("t.Do(1)")

	if !s.Save {
		// GetList := {}
		g.writeln("t.PushValue(hbrt.MakeArray(0))")
		g.emitPopByName("GetList", locals)
	}
}

// emitGetSetBlock generates a {|_1| IIF(_1 == NIL, var, var := _1)} code block.
// Uses captured frame base + local index to access the outer variable correctly
// even when the block is called from a different call depth (e.g., Eval inside GetNew).
func (g *Generator) emitGetSetBlock(varExpr ast.Expr, varName string, locals localMap) {
	if idx, found := locals[varName]; found {
		// Capture the frame's localBase and index at block creation time
		g.writeln(fmt.Sprintf("{ // GET/SET block for %s", varName))
		g.indent++
		g.writeln(fmt.Sprintf("_getIdx := %d", idx))
		g.writeln("_getFrame := t.CurFrame()")
		g.writeln("_getLocals := t.LocalsSlice()")
		g.writeln("t.PushBlock(func(t2 *hbrt.Thread) {")
		g.indent++
		g.writeln("t2.Frame(1, 0)")
		g.writeln("defer t2.EndProc()")
		g.writeln("if t2.Local(1).IsNil() {")
		g.indent++
		g.writeln("t2.PushValue(_getFrame.GetLocal(_getIdx, _getLocals))")
		g.writeln("t2.RetValue()")
		g.indent--
		g.writeln("} else {")
		g.indent++
		g.writeln("_getFrame.SetLocal(_getIdx, t2.Local(1), _getLocals)")
		g.writeln("t2.PushValue(t2.Local(1))")
		g.writeln("t2.RetValue()")
		g.indent--
		g.writeln("}")
		g.indent--
		g.writeln("}, 0)")
		g.indent--
		g.writeln("}")
	} else {
		// Fallback: push NIL block
		g.writeln("t.PushNil() // GET block for unresolved var")
	}
}

// emitIdentByName pushes a variable by name onto the stack
func (g *Generator) emitIdentByName(name string, locals localMap) {
	if idx, found := locals[name]; found {
		g.writeln(fmt.Sprintf("t.PushLocal(%d)", idx))
	} else if goVar, found := g.staticVars[strings.ToUpper(name)]; found {
		g.writeln(fmt.Sprintf("t.PushValue(%s)", goVar))
	} else {
		g.writeln(fmt.Sprintf("t.PushLocal(0) // UNRESOLVED: %q", name))
	}
}

// emitPopByName pops stack into a variable by name
func (g *Generator) emitPopByName(name string, locals localMap) {
	if idx, found := locals[name]; found {
		g.writeln(fmt.Sprintf("t.PopLocal(%d)", idx))
	} else if goVar, found := g.staticVars[strings.ToUpper(name)]; found {
		g.writeln(fmt.Sprintf("%s = t.Pop2()", goVar))
	} else {
		g.writeln(fmt.Sprintf("t.Pop() // cannot assign to UNRESOLVED: %q", name))
	}
}