// Copyright (c) 2019-2022 Alexander Medvednikov. All rights reserved.
// Use of this source code is governed by an MIT license
// that can be found in the LICENSE file.
module c

import v.ast
import v.util
import v.token

fn (mut g Gen) gen_assign_stmt(node_ ast.AssignStmt) {
	mut node := unsafe { node_ }
	if node.is_static {
		g.write('static ')
	}
	if node.is_volatile {
		g.write('volatile ')
	}
	mut return_type := ast.void_type
	is_decl := node.op == .decl_assign
	g.assign_op = node.op
	defer {
		g.assign_op = .unknown
	}
	op := if is_decl { token.Kind.assign } else { node.op }
	right_expr := node.right[0]
	match right_expr {
		ast.CallExpr { return_type = right_expr.return_type }
		ast.LockExpr { return_type = right_expr.typ }
		ast.MatchExpr { return_type = right_expr.return_type }
		ast.IfExpr { return_type = right_expr.typ }
		else {}
	}
	// Free the old value assigned to this string var (only if it's `str = [new value]`
	// or `x.str = [new value]` )
	mut af := g.is_autofree && !g.is_builtin_mod && node.op == .assign && node.left_types.len == 1
		&& (node.left[0] is ast.Ident || node.left[0] is ast.SelectorExpr)
	// node.left_types[0] in [ast.string_type, ast.array_type] &&
	mut sref_name := ''
	mut type_to_free := ''
	if af {
		first_left_type := node.left_types[0]
		first_left_sym := g.table.sym(node.left_types[0])
		if first_left_type == ast.string_type || first_left_sym.kind == .array {
			type_to_free = if first_left_type == ast.string_type { 'string' } else { 'array' }
			mut ok := true
			left0 := node.left[0]
			if left0 is ast.Ident {
				if left0.name == '_' {
					ok = false
				}
			}
			if ok {
				sref_name = '_sref$node.pos.pos'
				g.write('$type_to_free $sref_name = (') // TODO we are copying the entire string here, optimize
				// we can't just do `.str` since we need the extra data from the string struct
				// doing `&string` is also not an option since the stack memory with the data will be overwritten
				g.expr(left0) // node.left[0])
				g.writeln('); // free $type_to_free on re-assignment2')
				defer {
					if af {
						g.writeln('${type_to_free}_free(&$sref_name);')
					}
				}
			} else {
				af = false
			}
		} else {
			af = false
		}
	}
	g.gen_assign_vars_autofree(node)
	// json_test failed w/o this check
	if return_type != ast.void_type && return_type != 0 {
		sym := g.table.sym(return_type)
		if sym.kind == .multi_return {
			g.gen_multi_return_assign(node, return_type)
			return
		}
	}
	// TODO: non idents on left (exprs)
	if node.has_cross_var {
		g.gen_cross_var_assign(node)
	}
	// `a := 1` | `a,b := 1,2`
	if node.right.len < node.left.len {
		g.checker_bug('node.right.len < node.left.len', node.pos)
	}
	if node.right_types.len < node.left.len {
		g.checker_bug('node.right_types.len < node.left.len', node.pos)
	}
	if node.left_types.len < node.left.len {
		g.checker_bug('node.left_types.len < node.left.len', node.pos)
	}

	for i, mut left in node.left {
		mut is_auto_heap := false
		mut var_type := node.left_types[i]
		mut val_type := node.right_types[i]
		val := node.right[i]
		mut is_call := false
		mut blank_assign := false
		mut ident := ast.Ident{
			scope: 0
		}
		left_sym := g.table.sym(g.unwrap_generic(var_type))
		if mut left is ast.Ident {
			ident = left
			// id_info := ident.var_info()
			// var_type = id_info.typ
			blank_assign = left.kind == .blank_ident
			// TODO: temporary, remove this
			left_info := left.info
			if left_info is ast.IdentVar {
				share := left_info.share
				if share == .shared_t {
					var_type = var_type.set_flag(.shared_f)
				}
				if share == .atomic_t {
					var_type = var_type.set_flag(.atomic_f)
				}
			}
			if mut left.obj is ast.Var {
				if val is ast.ComptimeSelector {
					if val.field_expr is ast.SelectorExpr {
						if val.field_expr.expr is ast.Ident {
							key_str := '${val.field_expr.expr.name}.typ'
							var_type = g.comptime_var_type_map[key_str] or { var_type }
							left.obj.typ = var_type
						}
					}
				} else if val is ast.ComptimeCall {
					key_str := '${val.method_name}.return_type'
					var_type = g.comptime_var_type_map[key_str] or { var_type }
					left.obj.typ = var_type
				}
				is_auto_heap = left.obj.is_auto_heap
			}
		}
		styp := g.typ(var_type)
		mut is_fixed_array_init := false
		mut has_val := false
		match val {
			ast.ArrayInit {
				is_fixed_array_init = val.is_fixed
				has_val = val.has_val
			}
			ast.CallExpr {
				is_call = true
				return_type = val.return_type
			}
			// TODO: no buffer fiddling
			ast.AnonFn {
				if blank_assign {
					g.write('{')
				}
				// if it's a decl assign (`:=`) or a blank assignment `_ =`/`_ :=` then generate `void (*ident) (args) =`
				if (is_decl || blank_assign) && left is ast.Ident {
					ret_styp := g.typ(val.decl.return_type)
					g.write('$ret_styp (*$ident.name) (')
					def_pos := g.definitions.len
					g.fn_decl_params(val.decl.params, voidptr(0), false)
					g.definitions.go_back(g.definitions.len - def_pos)
					g.write(') = ')
				} else {
					g.is_assign_lhs = true
					g.assign_op = node.op
					g.expr(left)
					g.is_assign_lhs = false
					g.is_arraymap_set = false
					if mut left is ast.IndexExpr {
						sym := g.table.sym(left.left_type)
						if sym.kind in [.map, .array] {
							g.expr(val)
							g.writeln('});')
							continue
						}
					}
					g.write(' = ')
				}
				g.expr(val)
				g.writeln(';')
				if blank_assign {
					g.write('}')
				}
				continue
			}
			else {}
		}
		unwrapped_val_type := g.unwrap_generic(val_type)
		right_sym := g.table.sym(unwrapped_val_type)
		unaliased_right_sym := g.table.final_sym(unwrapped_val_type)
		is_fixed_array_var := unaliased_right_sym.kind == .array_fixed && val !is ast.ArrayInit
			&& (val in [ast.Ident, ast.IndexExpr, ast.CallExpr, ast.SelectorExpr]
			|| (val is ast.CastExpr && (val as ast.CastExpr).expr !is ast.ArrayInit))
			&& !g.pref.translated
		g.is_assign_lhs = true
		g.assign_op = node.op
		if val_type.has_flag(.optional) {
			g.right_is_opt = true
		}
		if blank_assign {
			if val is ast.IndexExpr {
				g.assign_op = .decl_assign
			}
			g.is_assign_lhs = false
			if is_call {
				old_is_void_expr_stmt := g.is_void_expr_stmt
				g.is_void_expr_stmt = true
				g.expr(val)
				g.is_void_expr_stmt = old_is_void_expr_stmt
			} else if g.inside_for_c_stmt {
				g.expr(val)
			} else {
				if left_sym.kind == .function {
					g.write('{void* _ = ')
				} else {
					g.write('{$styp _ = ')
				}
				g.expr(val)
				g.writeln(';}')
			}
		} else if node.op == .assign && !g.pref.translated
			&& (is_fixed_array_init || (right_sym.kind == .array_fixed && val is ast.Ident)) {
			// Fixed arrays
			mut v_var := ''
			arr_typ := styp.trim('*')
			if is_fixed_array_init {
				right := val as ast.ArrayInit
				v_var = g.new_tmp_var()
				g.write('$arr_typ $v_var = ')
				g.expr(right)
				g.writeln(';')
			} else {
				right := val as ast.Ident
				v_var = right.name
			}
			pos := g.out.len
			g.expr(left)

			if g.is_arraymap_set && g.arraymap_set_pos > 0 {
				g.out.go_back_to(g.arraymap_set_pos)
				g.write(', &$v_var)')
				g.is_arraymap_set = false
				g.arraymap_set_pos = 0
			} else {
				g.out.go_back_to(pos)
				is_var_mut := !is_decl && left.is_auto_deref_var()
				addr_left := if is_var_mut { '' } else { '&' }
				g.writeln('')
				g.write('memcpy($addr_left')
				g.expr(left)
				addr_val := if is_fixed_array_var { '' } else { '&' }
				g.writeln(', $addr_val$v_var, sizeof($arr_typ));')
			}
			g.is_assign_lhs = false
		} else {
			is_inside_ternary := g.inside_ternary != 0
			cur_line := if is_inside_ternary && is_decl {
				g.register_ternary_name(ident.name)
				g.empty_line = false
				g.go_before_ternary()
			} else {
				''
			}
			mut str_add := false
			mut op_overloaded := false
			mut op_expected_left := ast.Type(0)
			mut op_expected_right := ast.Type(0)
			if var_type == ast.string_type_idx && node.op == .plus_assign {
				if left is ast.IndexExpr {
					// a[0] += str => `array_set(&a, 0, &(string[]) {string__plus(...))})`
					g.expr(left)
					g.write('string__plus(')
				} else {
					// str += str2 => `str = string__plus(str, str2)`
					g.expr(left)
					g.write(' = /*f*/string__plus(')
				}
				g.is_assign_lhs = false
				str_add = true
			}
			// Assignment Operator Overloading
			if ((left_sym.kind == .struct_ && right_sym.kind == .struct_)
				|| (left_sym.kind == .alias && right_sym.kind == .alias))
				&& node.op in [.plus_assign, .minus_assign, .div_assign, .mult_assign, .mod_assign] {
				extracted_op := match node.op {
					.plus_assign { '+' }
					.minus_assign { '-' }
					.div_assign { '/' }
					.mod_assign { '%' }
					.mult_assign { '*' }
					else { 'unknown op' }
				}
				g.expr(left)
				if left_sym.kind == .struct_ && (left_sym.info as ast.Struct).generic_types.len > 0 {
					concrete_types := (left_sym.info as ast.Struct).concrete_types
					mut method_name := left_sym.cname + '_' + util.replace_op(extracted_op)
					method_name = g.generic_fn_name(concrete_types, method_name, true)
					g.write(' = ${method_name}(')
					g.expr(left)
					g.write(', ')
					g.expr(val)
					g.writeln(');')
					return
				} else {
					g.write(' = ${styp}_${util.replace_op(extracted_op)}(')
					method := g.table.find_method(left_sym, extracted_op) or {
						// the checker will most likely have found this, already...
						g.error('assignment operator `$extracted_op=` used but no `$extracted_op` method defined',
							node.pos)
						ast.Fn{}
					}
					op_expected_left = method.params[0].typ
					op_expected_right = method.params[1].typ
					op_overloaded = true
				}
			}
			if right_sym.kind == .function && is_decl {
				if is_inside_ternary && is_decl {
					g.out.write_string(util.tabs(g.indent - g.inside_ternary))
				}
				func := right_sym.info as ast.FnType
				ret_styp := g.typ(func.func.return_type)

				mut call_conv := ''
				mut msvc_call_conv := ''
				for attr in func.func.attrs {
					match attr.name {
						'callconv' {
							if g.is_cc_msvc {
								msvc_call_conv = '__$attr.arg '
							} else {
								call_conv = '$attr.arg'
							}
						}
						else {}
					}
				}
				call_conv_attribute_suffix := if call_conv.len != 0 {
					'__attribute__(($call_conv))'
				} else {
					''
				}

				g.write('$ret_styp ($msvc_call_conv*${g.get_ternary_name(ident.name)}) (')
				def_pos := g.definitions.len
				g.fn_decl_params(func.func.params, voidptr(0), false)
				g.definitions.go_back(g.definitions.len - def_pos)
				g.write(')$call_conv_attribute_suffix')
			} else {
				if is_decl {
					if is_inside_ternary {
						g.out.write_string(util.tabs(g.indent - g.inside_ternary))
					}
					mut is_used_var_styp := false
					if ident.name !in g.defer_vars {
						val_sym := g.table.sym(val_type)
						if val_sym.info is ast.Struct {
							if val_sym.info.generic_types.len > 0 {
								if val is ast.StructInit {
									var_styp := g.typ(val.typ)
									g.write('$var_styp ')
									is_used_var_styp = true
								} else if val is ast.PrefixExpr {
									if val.op == .amp && val.right is ast.StructInit {
										var_styp := g.typ(val.right.typ.ref())
										g.write('$var_styp ')
										is_used_var_styp = true
									}
								}
							}
						}
						if !is_used_var_styp {
							g.write('$styp ')
						}
						if is_auto_heap {
							g.write('*')
						}
					}
				}
				if left in [ast.Ident, ast.SelectorExpr] {
					g.prevent_sum_type_unwrapping_once = true
				}
				if !is_fixed_array_var || is_decl {
					if op_overloaded {
						g.op_arg(left, op_expected_left, var_type)
					} else {
						if !is_decl && left.is_auto_deref_var() {
							g.write('*')
						}
						g.expr(left)
					}
				}
			}
			if is_inside_ternary && is_decl {
				g.write(';\n$cur_line')
				g.out.write_string(util.tabs(g.indent))
				g.expr(left)
			}
			g.is_assign_lhs = false
			if is_fixed_array_var {
				if is_decl {
					g.writeln(';')
				}
			} else if !g.is_arraymap_set && !str_add && !op_overloaded {
				g.write(' $op ')
			} else if str_add || op_overloaded {
				g.write(', ')
			}
			mut cloned := false
			if g.is_autofree && right_sym.kind in [.array, .string]
				&& !unwrapped_val_type.has_flag(.shared_f) {
				if g.gen_clone_assignment(val, unwrapped_val_type, false) {
					cloned = true
				}
			}
			unwrap_optional := !var_type.has_flag(.optional) && val_type.has_flag(.optional)
			if unwrap_optional {
				// Unwrap the optional now that the testing code has been prepended.
				// `pos := s.index(...
				// `int pos = *(int)_t10.data;`
				// if g.is_autofree {
				/*
				if is_optional {
					g.write('*($styp*)')
					g.write(tmp_opt + '.data/*FFz*/')
					g.right_is_opt = false
					if g.inside_ternary == 0 && !node.is_simple {
						g.writeln(';')
					}
					return
				}
				*/
			}
			g.is_shared = var_type.has_flag(.shared_f)
			if !cloned {
				if is_fixed_array_var {
					// TODO Instead of the translated check, check if it's a pointer already
					// and don't generate memcpy &
					typ_str := g.typ(val_type).trim('*')
					ref_str := if val_type.is_ptr() { '' } else { '&' }
					g.write('memcpy(($typ_str*)')
					g.expr(left)
					g.write(', (byte*)$ref_str')
					g.expr(val)
					g.write(', sizeof($typ_str))')
				} else if is_decl {
					if is_fixed_array_init && !has_val {
						if val is ast.ArrayInit {
							g.array_init(val, ident.name)
						} else {
							g.write('{0}')
						}
					} else {
						if is_auto_heap {
							g.write('HEAP($styp, (')
						}
						if val.is_auto_deref_var() {
							g.write('*')
						}
						if val is ast.ArrayInit {
							g.array_init(val, ident.name)
						} else if val_type.has_flag(.shared_f) {
							g.expr_with_cast(val, val_type, var_type)
						} else {
							g.expr(val)
						}
						if is_auto_heap {
							g.write('))')
						}
					}
				} else {
					if node.has_cross_var {
						g.gen_cross_tmp_variable(node.left, val)
					} else {
						if op_overloaded {
							g.op_arg(val, op_expected_right, val_type)
						} else {
							exp_type := if left.is_auto_deref_var() {
								var_type.deref()
							} else {
								var_type
							}
							g.expr_with_cast(val, val_type, exp_type)
						}
					}
				}
			}
			if str_add || op_overloaded {
				g.write(')')
			}
			if g.is_arraymap_set {
				g.write(' })')
				g.is_arraymap_set = false
			}
			g.is_shared = false
		}
		g.right_is_opt = false
		if g.inside_ternary == 0 && (node.left.len > 1 || !node.is_simple) {
			g.writeln(';')
		}
	}
}

fn (mut g Gen) gen_multi_return_assign(node &ast.AssignStmt, return_type ast.Type) {
	// multi return
	// TODO Handle in if_expr
	is_opt := return_type.has_flag(.optional)
	mr_var_name := 'mr_$node.pos.pos'
	mr_styp := g.typ(return_type.clear_flag(.optional))
	g.write('$mr_styp $mr_var_name = ')
	g.expr(node.right[0])
	g.writeln(';')
	for i, lx in node.left {
		mut is_auto_heap := false
		mut ident := ast.Ident{
			scope: 0
		}
		if lx is ast.Ident {
			ident = lx
			if lx.kind == .blank_ident {
				continue
			}
			if lx.obj is ast.Var {
				is_auto_heap = lx.obj.is_auto_heap
			}
		}
		styp := if ident.name in g.defer_vars { '' } else { g.typ(node.left_types[i]) }
		if node.op == .decl_assign {
			g.write('$styp ')
			if is_auto_heap {
				g.write('*')
			}
		}
		if lx.is_auto_deref_var() {
			g.write('*')
		}
		g.expr(lx)
		noscan := if is_auto_heap { g.check_noscan(return_type) } else { '' }
		if g.is_arraymap_set {
			if is_opt {
				mr_base_styp := g.base_type(return_type)
				if is_auto_heap {
					g.writeln('HEAP${noscan}($mr_base_styp, ${mr_var_name}.arg$i) });')
				} else {
					g.writeln('${mr_var_name}.arg$i });')
				}
			} else {
				if is_auto_heap {
					g.writeln('HEAP${noscan}($styp, ${mr_var_name}.arg$i) });')
				} else {
					g.writeln('${mr_var_name}.arg$i });')
				}
			}
		} else {
			if is_opt {
				mr_base_styp := g.base_type(return_type)
				if is_auto_heap {
					g.writeln(' = HEAP${noscan}($mr_base_styp, ${mr_var_name}.arg$i);')
				} else {
					g.writeln(' = ${mr_var_name}.arg$i;')
				}
			} else {
				if is_auto_heap {
					g.writeln(' = HEAP${noscan}($styp, ${mr_var_name}.arg$i);')
				} else {
					g.writeln(' = ${mr_var_name}.arg$i;')
				}
			}
		}
	}
	if g.is_arraymap_set {
		g.is_arraymap_set = false
	}
}

fn (mut g Gen) gen_assign_vars_autofree(node &ast.AssignStmt) {
	// Autofree tmp arg vars
	// first_right := node.right[0]
	// af := g.autofree && first_right is ast.CallExpr && !g.is_builtin_mod
	// if af {
	// g.autofree_call_pregen(first_right as ast.CallExpr)
	// }
	//
	//
	// Handle optionals. We need to declare a temp variable for them, that's why they are handled
	// here, not in call_expr().
	// `pos := s.index('x') or { return }`
	// ==========>
	// Option_int _t190 = string_index(s, _STR("x")); // _STR() no more used!!
	// if (_t190.state != 2) {
	// Error err = _t190.err;
	// return;
	// }
	// int pos = *(int*)_t190.data;
	// mut tmp_opt := ''
	/*
	is_optional := false && g.is_autofree && (node.op in [.decl_assign, .assign])
		&& node.left_types.len == 1 && node.right[0] is ast.CallExpr
	if is_optional {
		// g.write('/* optional assignment */')
		call_expr := node.right[0] as ast.CallExpr
		if call_expr.or_block.kind != .absent {
			styp := g.typ(call_expr.return_type.set_flag(.optional))
			tmp_opt = g.new_tmp_var()
			g.write('/*AF opt*/$styp $tmp_opt = ')
			g.expr(node.right[0])
			g.or_block(tmp_opt, call_expr.or_block, call_expr.return_type)
			g.writeln('/*=============ret*/')
			// if af && is_optional {
			// g.autofree_call_postgen()
			// }
			// return
		}
	}
	*/
}

fn (mut g Gen) gen_cross_var_assign(node &ast.AssignStmt) {
	for i, left in node.left {
		match left {
			ast.Ident {
				left_typ := node.left_types[i]
				left_sym := g.table.sym(left_typ)
				if left_sym.kind == .function {
					g.write_fn_ptr_decl(left_sym.info as ast.FnType, '_var_$left.pos.pos')
					g.writeln(' = ${c_name(left.name)};')
				} else {
					styp := g.typ(left_typ)
					g.writeln('$styp _var_$left.pos.pos = ${c_name(left.name)};')
				}
			}
			ast.IndexExpr {
				sym := g.table.sym(left.left_type)
				if sym.kind == .array {
					info := sym.info as ast.Array
					elem_typ := g.table.sym(info.elem_type)
					if elem_typ.kind == .function {
						left_typ := node.left_types[i]
						left_sym := g.table.sym(left_typ)
						g.write_fn_ptr_decl(left_sym.info as ast.FnType, '_var_$left.pos.pos')
						g.write(' = *(voidptr*)array_get(')
					} else {
						styp := g.typ(info.elem_type)
						g.write('$styp _var_$left.pos.pos = *($styp*)array_get(')
					}
					if left.left_type.is_ptr() {
						g.write('*')
					}
					needs_clone := info.elem_type == ast.string_type && g.is_autofree
					if needs_clone {
						g.write('/*1*/string_clone(')
					}
					g.expr(left.left)
					if needs_clone {
						g.write(')')
					}
					g.write(', ')
					g.expr(left.index)
					g.writeln(');')
				} else if sym.kind == .map {
					info := sym.info as ast.Map
					skeytyp := g.typ(info.key_type)
					styp := g.typ(info.value_type)
					zero := g.type_default(info.value_type)
					val_typ := g.table.sym(info.value_type)
					if val_typ.kind == .function {
						left_type := node.left_types[i]
						left_sym := g.table.sym(left_type)
						g.write_fn_ptr_decl(left_sym.info as ast.FnType, '_var_$left.pos.pos')
						g.write(' = *(voidptr*)map_get(')
					} else {
						g.write('$styp _var_$left.pos.pos = *($styp*)map_get(')
					}
					if !left.left_type.is_ptr() {
						g.write('ADDR(map, ')
						g.expr(left.left)
						g.write(')')
					} else {
						g.expr(left.left)
					}
					g.write(', &($skeytyp[]){')
					g.expr(left.index)
					g.write('}')
					if val_typ.kind == .function {
						g.writeln(', &(voidptr[]){ $zero });')
					} else {
						g.writeln(', &($styp[]){ $zero });')
					}
				}
			}
			ast.SelectorExpr {
				styp := g.typ(left.typ)
				g.write('$styp _var_$left.pos.pos = ')
				g.expr(left.expr)
				mut sel := '.'
				if left.expr_type.is_ptr() {
					if left.expr_type.has_flag(.shared_f) {
						sel = '->val.'
					} else {
						sel = '->'
					}
				}
				g.writeln('$sel$left.field_name;')
			}
			else {}
		}
	}
}

fn (mut g Gen) gen_cross_tmp_variable(left []ast.Expr, val ast.Expr) {
	val_ := val
	match val {
		ast.Ident {
			mut has_var := false
			for lx in left {
				if lx is ast.Ident {
					if val.name == lx.name {
						g.write('_var_')
						g.write(lx.pos.pos.str())
						has_var = true
						break
					}
				}
			}
			if !has_var {
				g.expr(val_)
			}
		}
		ast.IndexExpr {
			mut has_var := false
			for lx in left {
				if val_.str() == lx.str() {
					g.write('_var_')
					g.write(lx.pos().pos.str())
					has_var = true
					break
				}
			}
			if !has_var {
				g.expr(val_)
			}
		}
		ast.InfixExpr {
			sym := g.table.sym(val.left_type)
			if _ := g.table.find_method(sym, val.op.str()) {
				left_styp := g.typ(val.left_type.set_nr_muls(0))
				g.write(left_styp)
				g.write('_')
				g.write(util.replace_op(val.op.str()))
				g.write('(')
				g.gen_cross_tmp_variable(left, val.left)
				g.write(', ')
				g.gen_cross_tmp_variable(left, val.right)
				g.write(')')
			} else {
				g.gen_cross_tmp_variable(left, val.left)
				g.write(val.op.str())
				g.gen_cross_tmp_variable(left, val.right)
			}
		}
		ast.PrefixExpr {
			g.write(val.op.str())
			g.gen_cross_tmp_variable(left, val.right)
		}
		ast.PostfixExpr {
			g.gen_cross_tmp_variable(left, val.expr)
			g.write(val.op.str())
		}
		ast.SelectorExpr {
			mut has_var := false
			for lx in left {
				if val_.str() == lx.str() {
					g.write('_var_')
					g.write(lx.pos().pos.str())
					has_var = true
					break
				}
			}
			if !has_var {
				g.expr(val_)
			}
		}
		else {
			g.expr(val_)
		}
	}
}