#include <stdlib.h>
#include <string.h>
#include <assert.h>
#include "compiler.h"
#include "symtab.h"


static void write_func_params(struct pair_tn *params, struct node *list) {
	if (list->type == N_LIST_END) return;
	assert(list->child1->type == N_VAR_DECL);
	params[0].type = list->child1->rtype;
	params[0].name = strdup(list->child1->name);
	write_func_params(params + 1, list->child2);
}

static bool oper_is_basic_arith(enum operator oper) {
	return oper == OP_ADD || oper == OP_SUB || oper == OP_MUL || oper == OP_DIV || oper == OP_MOD;
}

static bool oper_is_comparison(enum operator oper) {
	return oper == OP_EQ || oper == OP_NEQ ||
	       oper == OP_LT || oper == OP_GT ||
	       oper == OP_LEQ || oper == OP_GEQ;
}

static struct ref compile_expr(struct ir *ir, struct symtab *symtab, struct node *node);

static void compile_boolexpr(
		struct ir *ir, struct symtab *symtab, struct node *node, char *truedest, char *falsedest) {

	if (node->type == N_BINOP && oper_is_comparison(node->oper)) {
		struct ref r1 = compile_expr(ir, symtab, node->child1);
		struct ref r2 = compile_expr(ir, symtab, node->child2);
		ir_append(ir, irins_make_12(INS_CMP, r1, r2));
		enum condcode condcode;
		switch (node->oper) {
			case OP_EQ: condcode = CCNZ; break;
			case OP_NEQ: condcode = CCZ; break;
			case OP_LT: condcode = CCGE; break;
			case OP_GT: condcode = CCLE; break;
			case OP_LEQ: condcode = CCG; break;
			case OP_GEQ: condcode = CCL; break;
			default: assert(false);
		}
		ir_append(ir, irins_make_jcc(falsedest, condcode));
		ir_append(ir, irins_make_name(INS_JMP, truedest));
	} else if (node->type == N_BINOP && node->oper == OP_AND) {
		char *try2lbl = gen_label_name();
		compile_boolexpr(ir, symtab, node->child1, try2lbl, falsedest);
		ir_append(ir, irins_make_name(INS_LBL, try2lbl));
		compile_boolexpr(ir, symtab, node->child2, truedest, falsedest);
	} else if (node->type == N_BINOP && node->oper == OP_OR) {
		char *try2lbl = gen_label_name();
		compile_boolexpr(ir, symtab, node->child1, truedest, try2lbl);
		ir_append(ir, irins_make_name(INS_LBL, try2lbl));
		compile_boolexpr(ir, symtab, node->child2, truedest, falsedest);
	} else if (node->type == N_UNOP && node->oper == OP_NOT) {
		compile_boolexpr(ir, symtab, node->child1, falsedest, truedest);
	} else {
		struct ref ref = compile_expr(ir, symtab, node);
		ir_append(ir, irins_make_12(INS_TEST, ref, ref));
		ir_append(ir, irins_make_jcc(falsedest, CCZ));
		ir_append(ir, irins_make_name(INS_JMP, truedest));
	}
}

static struct ref compile_expr(struct ir *ir, struct symtab *symtab, struct node *node) {
	switch (node->type) {
		case N_NUM: {
			struct ref ref = ref_next_register();
			ir_append(ir, irins_make_01(INS_MOV, ref, ref_imm(node->value)));
			return ref;
		}

		case N_VAR: {
			struct symbol *sym = symtab_find(symtab, node->name);
			if (!sym) {
				fprintf(stderr, "Use of undeclared variable '%s'\n", node->name);
				exit(1);
			}
			return sym->ref;
		}

		case N_BINOP: {
			if (oper_is_basic_arith(node->oper)) {
				struct ref r0 = ref_next_register();
				struct ref r1 = compile_expr(ir, symtab, node->child1);
				struct ref r2 = compile_expr(ir, symtab, node->child2);
				enum instype instype;
				switch (node->oper) {
					case OP_ADD: instype = INS_ADD; break;
					case OP_SUB: instype = INS_SUB; break;
					case OP_MUL: instype = INS_MUL; break;
					case OP_DIV: instype = INS_DIV; break;
					case OP_MOD: instype = INS_MOD; break;
					default: assert(false);
				}
				ir_append(ir, irins_make_012(instype, r0, r1, r2));
				return r0;
			} else if (oper_is_comparison(node->oper) || node->oper == OP_AND || node->oper == OP_OR) {
				char *truelbl = gen_label_name();
				char *falselbl = gen_label_name();
				char *afterlbl = gen_label_name();
				compile_boolexpr(ir, symtab, node, truelbl, falselbl);
				struct ref cval = ref_next_register();
				ir_append(ir, irins_make_name(INS_LBL, truelbl));
				ir_append(ir, irins_make_01(INS_MOV, cval, ref_imm(1)));
				ir_append(ir, irins_make_name(INS_JMP, afterlbl));
				ir_append(ir, irins_make_name(INS_LBL, falselbl));
				ir_append(ir, irins_make_01(INS_MOV, cval, ref_imm(0)));
				ir_append(ir, irins_make_name(INS_LBL, afterlbl));
				return cval;
			} else if (node->oper == OP_ASSIGN) {
				if (node->child1->type == N_VAR ||
						(node->child1->type == N_UNOP && node->child1->oper == OP_DEREF)) {
					struct ref r0 = compile_expr(ir, symtab, node->child1);
					struct ref r1 = compile_expr(ir, symtab, node->child2);
					ir_append(ir, irins_make_01(INS_MOV, r0, r1));
					return r0;
				} else {
					fprintf(stderr, "Invalid left-hand side in assignment.\n");
					exit(1);
				}
			} else {
				assert(false);
			}
		}

		case N_UNOP: {
			switch (node->oper) {
				case OP_NEG: {
					struct ref r0 = ref_next_register();
					struct ref r1 = compile_expr(ir, symtab, node->child1);
					ir_append(ir, irins_make_01(INS_NEG, r0, r1));
					return r0;
				}

				case OP_NOT: {
					struct ref r0 = ref_next_register();
					struct ref r1 = compile_expr(ir, symtab, node->child1);
					ir_append(ir, irins_make_01(INS_NOT, r0, r1));
					return r0;
				}

				case OP_DEREF: {
					struct ref addr = compile_expr(ir, symtab, node->child1);
					struct ref r1;
					switch (addr.type) {
						case REF_REG: r1 = ref_mem(addr.reg, 0, false); break;
						case REF_IMM: r1 = ref_mem(-1, addr.imm, false); break;
						case REF_MEM: {
							r1 = ref_next_register();
							ir_append(ir, irins_make_01(INS_MOV, r1, addr));
							r1 = ref_mem(r1.reg, 0, false); break;
							break;
						}
					}
					struct ref r0 = ref_next_register();
					ir_append(ir, irins_make_01(INS_MOV, r0, r1));
					return r0;
				}

				case OP_ADDROF:
					fprintf(stderr, "OP_ADDROF not implemented\n");
					exit(1);

				default:
					assert(false);
			}
		}

		case N_CALL: {
			fprintf(stderr, "function calls not implemented\n");
			exit(1);
			/*struct symbol *sym = symtab_find(symtab, node->name);
			if (!sym) {
				fprintf(stderr, "Call of undeclared function '%s'\n", node->name);
				exit(1);
			}
			;*/
		}

		default:
			fprintf(stderr, "Invalid node type %d in expression\n", node->type);
			exit(1);
	}
}

static void compile_node(struct ir *ir, struct symtab *symtab, struct node *node) {
	switch (node->type) {
		case N_LIST:
			compile_node(ir, symtab, node->child1);
			compile_node(ir, symtab, node->child2);
			break;

		case N_LIST_END:
			break;

		case N_BLOCK: {
			symtab = symtab_sub(symtab);
			compile_node(ir, symtab, node->child1);
			symtab = symtab_delete_get_parent(symtab);
			break;
		}

		case N_VAR_DECL_INIT:
		case N_VAR_DECL: {
			if (symtab_find_local(symtab, node->name)) {
				fprintf(stderr, "Redeclaration of variable '%s'\n", node->name);
				exit(1);
			}
			struct symbol *sym = symbol_make_var(node->name, node->rtype);
			sym->ref = ref_next_register();
			symtab_insert(symtab, sym);
			ir_append(ir, irins_make_01(INS_MOV, sym->ref, ref_imm(node->value)));
			break;
		}

		case N_FUNC_DECL: {
			if (symtab_find(symtab, node->name)) {
				fprintf(stderr, "Redeclaration of function '%s'\n", node->name);
				exit(1);
			}
			int numparams = node_list_length(node->child1);
			struct symbol *sym = symbol_make_func(node->name, node->rtype, numparams);
			write_func_params(sym->params, node->child1);
			symtab_insert(symtab_root(symtab), sym);
			ir_append(ir, irins_make_name(INS_LBL, strdup(node->name)));
			symtab = symtab_sub(symtab);
			compile_node(ir, symtab, node->child2);
			symtab = symtab_delete_get_parent(symtab);
			break;
		}

		case N_IF: {
			char *elselbl = gen_label_name();
			char *afterlbl = gen_label_name();
			struct ref condref = compile_expr(ir, symtab, node->child1);
			ir_append(ir, irins_make_12(INS_TEST, condref, condref));
			ir_append(ir, irins_make_jcc(elselbl, CCZ));
			compile_node(ir, symtab, node->child2);
			ir_append(ir, irins_make_name(INS_JMP, afterlbl));
			ir_append(ir, irins_make_name(INS_LBL, elselbl));
			compile_node(ir, symtab, node->child3);
			ir_append(ir, irins_make_name(INS_LBL, afterlbl));
			break;
		}

		case N_WHILE: {
			char *startlbl = gen_label_name();
			char *afterlbl = gen_label_name();
			ir_append(ir, irins_make_name(INS_LBL, startlbl));
			struct ref condref = compile_expr(ir, symtab, node->child1);
			ir_append(ir, irins_make_12(INS_TEST, condref, condref));
			ir_append(ir, irins_make_jcc(afterlbl, CCZ));
			compile_node(ir, symtab, node->child2);
			ir_append(ir, irins_make_name(INS_JMP, startlbl));
			ir_append(ir, irins_make_name(INS_LBL, afterlbl));
			break;
		}

		case N_RETURN: {
			struct ref ref = compile_expr(ir, symtab, node->child1);
			ir_append(ir, irins_make_1(INS_RETV, ref));
			break;
		}

		default:  // hmm, maybe it's an expression statement?
			compile_expr(ir, symtab, node);
			break;
	}
}

struct ir* compile(struct node *node) {
	struct ir *ir = ir_make();
	struct symtab *symtab = symtab_make();
	compile_node(ir, symtab, node);
	return ir;
}