// 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
	}
	shared := "false"
	if s.Shared {
		shared = "true"
	}
	readOnly := "false"
	if s.ReadOnly {
		readOnly = "true"
	}

	if s.AliasExpr != nil {
		// Dynamic alias: ALIAS (expr)
		g.emitExpr(s.AliasExpr)
		g.writeln("_alias := t.Pop2().AsString()")
		g.writeln(fmt.Sprintf("_, _err := wa.Open(%q, _path, _alias, %s, %s)", via, shared, readOnly))
	} else {
		g.writeln(fmt.Sprintf("_, _err := wa.Open(%q, _path, %q, %s, %s)", via, s.Alias, shared, readOnly))
	}
	g.writeln("if _err != nil { panic(&hbrt.HbError{Description: _err.Error(), Operation: \"USE\", SubSystem: \"BASE\"}) }")
	g.indent--
	g.writeln("}")
}

func (g *Generator) emitGoCmd(s *ast.GoCmd) {
	// Use hoisted area if available
	areaVar := "_area"
	if g.hoistedDW || g.hoistedFields != nil {
		areaVar = g.hoistedAreaVar()
		g.writeln(fmt.Sprintf("if %s != nil {", areaVar))
		g.indent++
	} else {
		g.writeln("{")
		g.indent++
		g.writeln("wa := t.WA.(*hbrdd.WorkAreaManager)")
		g.writeln(fmt.Sprintf("if %s := wa.Current(); %s != nil {", areaVar, areaVar))
		g.indent++
	}

	switch s.Direction {
	case "TOP":
		g.writeln(fmt.Sprintf("%s.GoTop()", areaVar))
	case "BOTTOM":
		g.writeln(fmt.Sprintf("%s.GoBottom()", areaVar))
	default:
		if s.RecNo != nil {
			if lit, ok := s.RecNo.(*ast.LiteralExpr); ok && lit.Kind == token.INT {
				g.writeln(fmt.Sprintf("%s.GoTo(uint32(%s))", areaVar, lit.Value))
			} else {
				g.emitExpr(s.RecNo)
				g.writeln(fmt.Sprintf("%s.GoTo(uint32(t.Pop2().AsNumInt()))", areaVar))
			}
		}
	}

	g.indent--
	g.writeln("}")
	if !g.hoistedDW && g.hoistedFields == nil {
		g.indent--
		g.writeln("}")
	}
}

func (g *Generator) emitSkipCmd(s *ast.SkipCmd, locals localMap) {
	areaVar := "_area"
	if g.hoistedDW || g.hoistedFields != nil {
		areaVar = g.hoistedAreaVar()
		g.writeln(fmt.Sprintf("if %s != nil {", areaVar))
		g.indent++
	} else {
		g.writeln("{")
		g.indent++
		g.writeln("wa := t.WA.(*hbrdd.WorkAreaManager)")
		g.writeln(fmt.Sprintf("if %s := wa.Current(); %s != nil {", areaVar, areaVar))
		g.indent++
	}

	if s.Count != nil {
		if lit, ok := s.Count.(*ast.LiteralExpr); ok && lit.Kind == token.INT {
			g.writeln(fmt.Sprintf("%s.Skip(%s)", areaVar, lit.Value))
		} else if unary, ok := s.Count.(*ast.UnaryExpr); ok {
			if lit2, ok2 := unary.X.(*ast.LiteralExpr); ok2 && lit2.Kind == token.INT {
				g.writeln(fmt.Sprintf("%s.Skip(-%s)", areaVar, lit2.Value))
			} else {
				g.emitExpr(s.Count)
				g.writeln(fmt.Sprintf("%s.Skip(t.Pop2().AsNumInt())", areaVar))
			}
		} else {
			g.emitExpr(s.Count)
			g.writeln(fmt.Sprintf("%s.Skip(t.Pop2().AsNumInt())", areaVar))
		}
	} else {
		g.writeln(fmt.Sprintf("%s.Skip(1)", areaVar))
	}

	g.indent--
	g.writeln("}")
	if !g.hoistedDW && g.hoistedFields == nil {
		g.indent--
		g.writeln("}")
	}
}

// hoistedAreaVar returns the area variable name for the current hoisting context.
func (g *Generator) hoistedAreaVar() string {
	if g.hoistedFields != nil {
		return "_rarea"
	}
	return "_darea"
}

func (g *Generator) emitSeekCmd(s *ast.SeekCmd, locals localMap) {
	areaVar := "area"
	if g.hoistedDW || g.hoistedFields != nil {
		areaVar = g.hoistedAreaVar()
		g.writeln(fmt.Sprintf("if %s != nil {", areaVar))
		g.indent++
	} else {
		g.writeln("{")
		g.indent++
		g.writeln("wa := t.WA.(*hbrdd.WorkAreaManager)")
		g.writeln(fmt.Sprintf("if %s := wa.Current(); %s != nil {", areaVar, areaVar))
		g.indent++
	}

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

	g.indent--
	g.writeln("}")
	if !g.hoistedDW && g.hoistedFields == nil {
		g.indent--
		g.writeln("}")
	}
}

func (g *Generator) emitReplaceCmd(s *ast.ReplaceCmd, locals localMap) {
	// Check if we're inside a hoisted FOR loop
	if g.hoistedFields != nil {
		g.emitReplaceCmdHoisted(s, locals)
		return
	}

	g.writeln("{")
	g.indent++
	g.writeln("wa := t.WA.(*hbrdd.WorkAreaManager)")
	g.writeln("if _area := wa.Current(); _area != nil {")
	g.indent++
	g.writeln("_dbf, _ := _area.(*dbf.DBFArea)")
	g.writeln("if _dbf != nil {")
	g.indent++

	for _, rf := range s.Fields {
		if ident, ok := rf.Field.(*ast.IdentExpr); ok {
			g.emitExpr(rf.Value)
			g.writeln(fmt.Sprintf("_dbf.PutValue(_dbf.FieldIndex(%q), t.Pop2())", ident.Name))
		}
	}

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

// emitReplaceCmdHoisted emits REPLACE using pre-hoisted _rdbf and _rfiN variables.
func (g *Generator) emitReplaceCmdHoisted(s *ast.ReplaceCmd, locals localMap) {
	g.writeln("if _rdbf != nil {")
	g.indent++
	for _, rf := range s.Fields {
		if ident, ok := rf.Field.(*ast.IdentExpr); ok {
			// Find cached field index variable
			fiVar := ""
			for i, fname := range g.hoistedFields {
				if strings.EqualFold(fname, ident.Name) {
					fiVar = fmt.Sprintf("_rfi%d", i)
					break
				}
			}
			if fiVar != "" {
				g.emitExpr(rf.Value)
				g.writeln(fmt.Sprintf("_rdbf.PutValue(%s, t.Pop2())", fiVar))
			} else {
				// Field not in hoisted set — fallback
				g.emitExpr(rf.Value)
				g.writeln(fmt.Sprintf("_rdbf.PutValue(_rdbf.FieldIndex(%q), t.Pop2())", ident.Name))
			}
		}
	}
	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[strings.ToUpper(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[strings.ToUpper(name)]; found {
		g.writeln(fmt.Sprintf("t.PushLocalFast(%d)", idx))
	} else if goVar, found := g.staticVars[strings.ToUpper(name)]; found {
		g.writeln(fmt.Sprintf("t.PushValue(%s)", goVar))
	} else {
		// Unresolved → runtime memvar lookup (returns NIL if missing).
		g.writeln(fmt.Sprintf("t.PushMemvar(%q) // unresolved", name))
	}
}

// emitPopByName pops stack into a variable by name
func (g *Generator) emitPopByName(name string, locals localMap) {
	if idx, found := locals[strings.ToUpper(name)]; found {
		g.writeln(fmt.Sprintf("t.PopLocalFast(%d)", idx))
	} else if goVar, found := g.staticVars[strings.ToUpper(name)]; found {
		g.writeln(fmt.Sprintf("%s = t.Pop2()", goVar))
	} else {
		// Unresolved → runtime memvar store (auto-creates PRIVATE).
		g.writeln(fmt.Sprintf("t.PopMemvar(%q) // unresolved", name))
	}
}