#include <assert.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <ctype.h>
#include <stdint.h>
#include <stdbool.h>
#include <stdarg.h>
#include "base.c"
#include "meta_gen.c"
#include "lex.c"

typedef struct Parser {
    Token *at;
    Token *end;
} Parser;

typedef enum Ast_Kind {
    AST_NONE,
    AST_ERROR,
    AST_INT,
    AST_UNARY,
    AST_BINARY,
} Ast_Kind;

typedef struct Ast Ast;
struct Ast {
    Ast_Kind kind;
    Token *pos;

    union {
        uint64_t u;
        struct {
            Token_Kind op;
            Ast *l;
            Ast *r;
        };
        char *error;
    };
};

Token *next_token(Parser *p) {
    if (p->at < p->end) {
        return p->at++;
    }
    return p->at;
}

Token *match_token(Parser *p, Token_Kind kind) {
    if (p->at->kind == kind) {
        return next_token(p);
    }
    return NULL;
}

Token *expect_token(Parser *p, Token_Kind kind) {
    if (p->at->kind == kind) {
        return next_token(p);
    }
    panicf("expected token kind: %s, got instead: %s", token_to_name(p->at->kind), token_to_name(kind));
}

Ast *create_ast(Token *token, Ast_Kind kind) {
    Ast *result = calloc(1, sizeof(Ast));
    result->pos = token;
    result->kind = kind;
    return result;
}

Ast *create_binary_expr(Token *token, Token_Kind op, Ast *left, Ast *right) {
    Ast *result = create_ast(token, AST_BINARY);
    result->op = op;
    result->l = left;
    result->r = right;
    return result;
}

Ast *parse_expr(Parser *p, int power_of_binding_to_right);

Ast *parse_atom(Parser *p) {
    Token *token = p->at;
    Ast *n = NULL;
    if (match_token(p, TOK_INT)) {
        n = create_ast(token, AST_INT);
        n->u = token->u;
    } else if (match_token(p, TOK_LPAREN)) {
        // @todo: do a comma list here
        n = parse_expr(p, 0);
        expect_token(p, TOK_RPAREN);
    } else {
        panicf("unknown token in %s. %.*s (%s/%d), ", __FUNCTION__, token->len, token->str, token_to_name(token->kind), token->kind);
    }
    return n;
}

int get_binding_power(Token *tok) {
    switch (tok->kind) {
        case TOK_STAR: case TOK_SLASH: case TOK_PERCENT: return 120;
        case TOK_PLUS: case TOK_MINUS: return 110;
        case TOK_LSHIFT: case TOK_RSHIFT: return 100;
        case TOK_LT: case TOK_LEQ: case TOK_GT: case TOK_GEQ: return 90;
        case TOK_EQ: case TOK_NEQ: return 80;
        case TOK_BITAND: return 70;
        case TOK_BITXOR: return 60;
        case TOK_BITOR: return 50;
        case TOK_AND: return 40;
        case TOK_OR: return 30;
        default: return 0;
    }
}

Ast *parse_valid_left_binding(Parser *p, Token *tok, Ast *left) {
    switch (tok->kind) {
        case TOK_PLUS: case TOK_MINUS: case TOK_STAR: case TOK_SLASH: case TOK_PERCENT:
        case TOK_EQ: case TOK_NEQ: case TOK_LT: case TOK_LEQ: case TOK_GT: case TOK_GEQ: case TOK_BITAND:
        case TOK_BITOR: case TOK_BITXOR: case TOK_AND: case TOK_OR: case TOK_LSHIFT: case TOK_RSHIFT: {
            return create_binary_expr(tok, tok->kind, left, parse_expr(p, get_binding_power(tok)));
        } break;
        default: panicf("unknown token in %s. %.*s (%s/%d), ", __FUNCTION__, tok->len, tok->str, token_to_name(tok->kind), tok->kind);
    }
    return NULL;
}

Ast *parse_expr(Parser *p, int power_of_binding_to_right) {
    Ast *n = parse_atom(p);
    while (get_binding_power(p->at) > power_of_binding_to_right) {
        Token *tok = next_token(p);
        n = parse_valid_left_binding(p, tok, n);
    }
    return n;
}

int64_t eval_expr(Ast *n) {
    switch (n->kind) {
        case AST_INT: return (int64_t)n->u;
        case AST_BINARY: {
            int64_t left = eval_expr(n->l);
            int64_t right = eval_expr(n->r);
            switch (n->op) {
                case TOK_PLUS: return left + right;
                case TOK_MINUS: return left - right;
                case TOK_STAR: return left * right;
                case TOK_SLASH: return left / right;
                case TOK_PERCENT: return left % right;
                case TOK_EQ: return left == right;
                case TOK_NEQ: return left != right;
                case TOK_LT: return left < right;
                case TOK_LEQ: return left <= right;
                case TOK_GT: return left > right;
                case TOK_GEQ: return left >= right;
                case TOK_BITAND: return left & right;
                case TOK_BITOR: return left | right;
                case TOK_BITXOR: return left ^ right;
                case TOK_AND: return left && right;
                case TOK_OR: return left || right;
                case TOK_LSHIFT: return left << right;
                case TOK_RSHIFT: return left >> right;
                default: panicf("invalid token kind in eval_expr, binary");
            }
        } break;
        default: panicf("invalid ast kind in eval_expr");
    }
}

void print_expr(Ast *n) {
    switch (n->kind) {
        case AST_INT: printf("%lu", n->u); break;
        case AST_BINARY: {
            print_expr(n->l);
            printf(" %s ", token_to_op(n->op));
            print_expr(n->r);
        } break;
        default: panicf("encountered invalid ast kind in %s of kind: %d\n", __FUNCTION__, n->kind);
    }
}

void parser_test(void) {
#define TEST_EVAL(expr) do { \
    Token_Array tokens = lex_file("eval_test", (#expr), strlen((#expr)));\
    Parser p = {tokens.data, tokens.data + tokens.len};\
    Ast *result = parse_expr(&p, 0);\
    int64_t left = eval_expr(result);\
    int64_t right = (expr);\
    if (left != right) {\
        printf("%s:%d expected: %ld, got: %ld\n    expression: ", __FILE__, __LINE__, left, right);\
        print_expr(result);\
        printf("\n");\
    }\
} while (0)

#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wparentheses"

    TEST_EVAL(32+5-4);
    TEST_EVAL(16/2/2);
    TEST_EVAL(9*4/6);
    TEST_EVAL(17%5);
    TEST_EVAL(5125-42|(4&3)^2|2%1242);
    TEST_EVAL((45%2)^(23&3));
    TEST_EVAL(1<16*2);
    TEST_EVAL(16>1+2);
    TEST_EVAL(4<=2+2);
    TEST_EVAL(5>=2+2);
    TEST_EVAL(4==2+2);
    TEST_EVAL(5!=2+2);
    TEST_EVAL(1+1+1+1+2-2-3-4-5);
    TEST_EVAL(5%2^5&6|3);
    TEST_EVAL(6&3);
    TEST_EVAL(6|3);
    TEST_EVAL(6^3);
    TEST_EVAL(1&&2);
    TEST_EVAL(0||3);
    TEST_EVAL(1||0&&0);
    TEST_EVAL(8<<2);
    TEST_EVAL(32>>3);
    TEST_EVAL((2+3)*(4+5));
    TEST_EVAL(9>3&1);
    TEST_EVAL(8|1<4);
    TEST_EVAL(7<=3+4);
    TEST_EVAL(8>=2*4);
    TEST_EVAL(4==2+2);
    TEST_EVAL(5!=2+2);
    TEST_EVAL(1&&2);
    TEST_EVAL(0||3);
    TEST_EVAL(1||0&&0);
    TEST_EVAL(8<<2);
    TEST_EVAL(32>>3);
    TEST_EVAL(1+2<<3);
    TEST_EVAL(16>>1+1);

#pragma clang diagnostic pop


    printf("parser tests passed\n");
}

void lex_test(void) {
    char *src = "12 + 34.5 * 6\n- 7 % 2 / 1 == 1 != 2 <= 3 >= 4 && 3 || 4 << 1 >> 2";
    Lexer lex = make_lexer("test.c", src, (int)strlen(src));

    assert_token(lex_token(&lex), TOK_INT, "12", 0, 0);
    assert_token(lex_token(&lex), TOK_PLUS, "+", 0, 3);
    assert_token(lex_token(&lex), TOK_FLOAT, "34.5", 0, 5);
    assert_token(lex_token(&lex), TOK_STAR, "*", 0, 10);
    assert_token(lex_token(&lex), TOK_INT, "6", 0, 12);
    assert_token(lex_token(&lex), TOK_MINUS, "-", 1, 0);
    assert_token(lex_token(&lex), TOK_INT, "7", 1, 2);
    assert_token(lex_token(&lex), TOK_PERCENT, "%", 1, 4);
    assert_token(lex_token(&lex), TOK_INT, "2", 1, 6);
    assert_token(lex_token(&lex), TOK_SLASH, "/", 1, 8);
    assert_token(lex_token(&lex), TOK_INT, "1", 1, 10);
    assert_token(lex_token(&lex), TOK_EQ, "==", 1, 12);
    assert_token(lex_token(&lex), TOK_INT, "1", 1, 15);
    assert_token(lex_token(&lex), TOK_NEQ, "!=", 1, 17);
    assert_token(lex_token(&lex), TOK_INT, "2", 1, 20);
    assert_token(lex_token(&lex), TOK_LEQ, "<=", 1, 22);
    assert_token(lex_token(&lex), TOK_INT, "3", 1, 25);
    assert_token(lex_token(&lex), TOK_GEQ, ">=", 1, 27);
    assert_token(lex_token(&lex), TOK_INT, "4", 1, 30);
    assert_token(lex_token(&lex), TOK_AND, "&&", 1, 32);
    assert_token(lex_token(&lex), TOK_INT, "3", 1, 35);
    assert_token(lex_token(&lex), TOK_OR, "||", 1, 37);
    assert_token(lex_token(&lex), TOK_INT, "4", 1, 40);
    assert_token(lex_token(&lex), TOK_LSHIFT, "<<", 1, 42);
    assert_token(lex_token(&lex), TOK_INT, "1", 1, 45);
    assert_token(lex_token(&lex), TOK_RSHIFT, ">>", 1, 47);
    assert_token(lex_token(&lex), TOK_INT, "2", 1, 50);

    Token eof = lex_token(&lex);
    assert(eof.kind == TOK_EOF);
    assert(eof.len == 0);
    assert(eof.line == 1);
    assert(eof.column == 51);

    Token_Array array = lex_file("test.c", src, (int)strlen(src));
    assert(array.len == 28);

    printf("lexer tests passed\n");
}

int main() {
    vec_test();
    lex_test();
    parser_test();
}