#define _POSIX_C_SOURCE 200809L

#include "exec/ast_exec_functions.h"

#include <err.h>
#include <errno.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <unistd.h>

#include "ast/ast_accessors.h"
#include "ast/ast_redirect.h"
#include "exec/ast_exec_redirs.h"
#include "lexer/expansion.h"
#include "utils/env.h"

#define XCODE_TOENV(R)                                                         \
    char buf[16] = { 0 };                                                      \
    sprintf(buf, "%d", (R));                                                   \
    env_set("?", buf)

static char **convert_args(struct string **args)
{
    size_t l = 0;
    while (args[l])
    {
        l++;
    }

    char **c_args = calloc(l + 1, sizeof(char *));
    if (!c_args)
    {
        errx(EXIT_FAILURE, "convert_args: calloc failed.");
    }

    for (size_t i = 0; i < l; i++)
    {
        c_args[i] = calloc(args[i]->length + 1, sizeof(char));
        if (!c_args[i])
        {
            errx(EXIT_FAILURE, "convert_args: calloc failed.");
        }
        c_args[i] = strncpy(c_args[i], args[i]->data, args[i]->length);
    }

    return c_args;
}

static void free_args(char **args)
{
    size_t i = 0;
    while (args[i])
    {
        free(args[i]);
        i++;
    }
    free(args);
}

static builtin fetch_builtin(struct string *s)
{
    if (!s)
    {
        return NULL;
    }
    if (STRINGS_ARE_EQUAL(s->data, "false"))
    {
        return my_false;
    }
    if (STRINGS_ARE_EQUAL(s->data, "true"))
    {
        return my_true;
    }
    if (STRINGS_ARE_EQUAL(s->data, "echo"))
    {
        return echo;
    }
    if (STRINGS_ARE_EQUAL(s->data, "."))
    {
        return dot;
    }
    if (STRINGS_ARE_EQUAL(s->data, "exit"))
    {
        return my_exit;
    }
    if (STRINGS_ARE_EQUAL(s->data, "cd"))
    {
        return cd;
    }
    if (STRINGS_ARE_EQUAL(s->data, "export"))
    {
        return export;
    }
    return NULL;
}

static int exec_program(struct string **args)
{
    char **argv = convert_args(args);
    if (!argv[0])
    {
        free_args(argv);
        return 127;
    }
    pid_t p = fork();
    if (!p)
    {
        execvp(argv[0], argv);
        if (errno == ENOEXEC)
        {
            fprintf(stderr,
                    "exec_program: the file \'%s\' is not executable.\n",
                    argv[0]);
            free_args(argv);
            exit(126);
        }
        fprintf(stderr, "exec_program: command \'%s\' not found.\n", argv[0]);
        free_args(argv);
        exit(127);
    }
    else
    {
        int status = 0;
        waitpid(p, &status, 0);
        free_args(argv);
        if (WIFEXITED(status))
        {
            return WEXITSTATUS(status);
        }
        return SHELL_FALSE;
    }
}

static struct string **_copy_args(struct string **args)
{
    size_t len = 0;
    while (args[len])
    {
        len++;
    }
    struct string **cpy = calloc(len + 1, sizeof(struct string *));
    for (size_t i = 0; i < len; i++)
    {
        cpy[i] = string_deepcopy(args[i]);
    }
    return cpy;
}

static void _free_str_args(struct string **args)
{
    size_t i = 0;
    while (args[i])
    {
        string_free(args[i]);
        i++;
    }
    free(args);
}

int exec_ast_command(struct ast *ast)
{
    union ast_caster ast_cast;
    ast_cast.ast = ast;
    struct string **cpy = _copy_args(ast_cast.ast_c->args);
    if (!ast_cast.ast_c->args)
    {
        _free_str_args(cpy);
        fprintf(stderr, "exec_ast_command: invalid args for a command exec.\n");
        XCODE_TOENV(SHELL_FALSE);
        return SHELL_FALSE;
    }

    size_t i = 0;
    size_t j = 0;
    while (ast_cast.ast_c->args[i])
    {
        struct string *cv = expand_word(ast_cast.ast_c->args[i]);
        if (cv->length > 0)
        {
            string_free(ast_cast.ast_c->args[j]);
            ast_cast.ast_c->args[j++] = cv;
        }
        else
        {
            string_free(cv);
        }
        i++;
    }
    while (ast_cast.ast_c->args[j])
    {
        string_free(ast_cast.ast_c->args[j]);
        ast_cast.ast_c->args[j++] = NULL;
    }
    if (i == 0)
    {
        // No args !
        XCODE_TOENV(SHELL_TRUE);
        return SHELL_TRUE;
    }
    builtin f = fetch_builtin(ast_cast.ast_c->args[0]);
    int r = SHELL_TRUE;
    if (f != NULL)
    {
        r = (*f)(ast_cast.ast_c->args + 1);
    }
    else
    {
        r = exec_program(ast_cast.ast_c->args);
    }
    _free_str_args(ast_cast.ast_c->args);
    ast_cast.ast_c->args = cpy;
    XCODE_TOENV(r);
    return r;
}

int exec_ast_list(struct ast *ast)
{
    union ast_caster ast_cast;
    ast_cast.ast = ast;
    int status = SHELL_TRUE;
    for (size_t i = 0; i < ast_cast.ast_l->nb_children; i++)
    {
        status = eval_ast(get_i(ast_cast.ast, i));
    }
    XCODE_TOENV(status);
    return status;
}

int exec_ast_if(struct ast *ast)
{
    int k = SHELL_TRUE;
    if (eval_ast(get_i(ast, 0)) == SHELL_TRUE)
    {
        k = eval_ast(get_i(ast, 1));
    }
    else
    {
        k = eval_ast(get_i(ast, 2));
    }
    XCODE_TOENV(k);
    return k;
}

int exec_ast_logical(struct ast *ast)
{
    union ast_caster ast_cast;
    ast_cast.ast = ast;
    int k = SHELL_TRUE;
    switch (ast_cast.ast_lo->type)
    {
    case TOKEN_NEG:
        k = !eval_ast(get_left(ast));
        break;
    case TOKEN_AND:
        if (eval_ast(get_left(ast)) == SHELL_TRUE)
        {
            k = eval_ast(get_right(ast));
            break;
        }
        k = SHELL_FALSE;
        break;
    case TOKEN_OR:
        if (eval_ast(get_left(ast)) == SHELL_FALSE)
        {
            k = eval_ast(get_right(ast));
            break;
        }
        k = SHELL_TRUE;
        break;
    default:
        errx(SHELL_FALSE,
             "exec_ast_logical: invalid token type for logical operation. Got: "
             "%d",
             ast_cast.ast_lo->type);
    }
    XCODE_TOENV(k);
    return k;
}

int exec_ast_pipe(struct ast *ast)
{
    union ast_caster ast_cast;
    ast_cast.ast = ast;

    struct ast *left = ast_cast.ast_p->left;
    struct ast *right = ast_cast.ast_p->right;
    if (!left || !right)
    {
        XCODE_TOENV(EXIT_FAILURE);
        return EXIT_FAILURE;
    }

    int fds[2];
    if (pipe(fds) == -1)
    {
        XCODE_TOENV(EXIT_FAILURE);
        return EXIT_FAILURE;
    }

    pid_t p1 = fork();
    if (!p1)
    {
        close(fds[0]);
        dup2(fds[1], STDOUT_FILENO);
        int r1 = eval_ast(left);
        exit(r1);
    }

    pid_t p2 = fork();
    if (!p2)
    {
        close(fds[1]);
        dup2(fds[0], STDIN_FILENO);
        int r2 = eval_ast(right);
        exit(r2);
    }

    close(fds[0]);
    close(fds[1]);

    int status = 0;
    waitpid(p1, &status, 0);
    waitpid(p2, &status, 0);

    if (WIFEXITED(status))
    {
        int k = WEXITSTATUS(status);
        XCODE_TOENV(k);
        return k;
    }
    XCODE_TOENV(SHELL_FALSE);
    return SHELL_FALSE;
}

inline static bool _is_a_std_fd(int fd)
{
    return fd >= STDIN_FILENO && fd <= STDERR_FILENO;
}

static int _exec_ast_redir(struct ast_redirection *ast, int left_fd,
                           int right_fd)
{
    // Save std fds
    int cpy_stdin = dup(STDIN_FILENO);
    int cpy_stdout = dup(STDOUT_FILENO);
    int cpy_stderr = dup(STDERR_FILENO);
    if (right_fd == CLOSE_FD)
    {
        close(left_fd);
    }
    else
    {
        dup2(right_fd, left_fd);
    }

    int r = eval_ast(ast->expr);

    if (!_is_a_std_fd(right_fd))
    {
        close(right_fd);
    }
    if (!_is_a_std_fd(left_fd))
    {
        close(left_fd);
    }

    // Restore std fds
    dup2(cpy_stdin, STDIN_FILENO);
    dup2(cpy_stdout, STDOUT_FILENO);
    dup2(cpy_stderr, STDERR_FILENO);
    XCODE_TOENV(r);
    return r;
}

int exec_ast_redirection(struct ast *ast)
{
    union ast_caster ast_cast;
    ast_cast.ast = ast;

    int left_fd = 0;
    int right_fd = 0;
    find_fds(ast_cast.ast_r->redirect, &left_fd, &right_fd);
    if (left_fd == BAD_FD || right_fd == BAD_FD)
    {
        fprintf(stderr, "redirection: bad fd.\n");
        XCODE_TOENV(SHELL_FALSE);
        return SHELL_FALSE;
    }

    int k = _exec_ast_redir(ast_cast.ast_r, left_fd, right_fd);
    XCODE_TOENV(k);
    return k;
}

int exec_ast_while(struct ast *ast)
{
    int k = SHELL_TRUE;
    while (true)
    {
        int r = eval_ast(((struct ast_while *)ast)->cond);
        if (r != SHELL_TRUE)
        {
            break;
        }
        k = eval_ast(((struct ast_while *)ast)->body);
    }
    XCODE_TOENV(k);
    return k;
}

int exec_ast_assign(struct ast *ast)
{
    struct ast_assign *ast_a = (struct ast_assign *)ast;
    struct string *expanded = expand_word(ast_a->val);
    env_set(ast_a->name->data, expanded->data);
    string_free(expanded);
    XCODE_TOENV(SHELL_TRUE);
    return SHELL_TRUE;
}

int exec_ast_for(struct ast *ast)
{
    if (!get_left(ast))
    {
        XCODE_TOENV(SHELL_TRUE);
        return SHELL_TRUE;
    }
    struct string **args = ((struct ast_command *)get_left(ast))->args;
    struct string *name = ((struct ast_for *)ast)->var;
    int k = SHELL_TRUE;
    size_t i = 0;
    while (args[i])
    {
        struct string *value = args[i];
        i++;
        env_set(name->data, value->data);
        k = eval_ast(get_right(ast));
    }
    XCODE_TOENV(k);
    return k;
}

static int _exec_fork(struct ast *ast)
{
    pid_t child = fork();

    if (child == -1)
    {
        XCODE_TOENV(SHELL_FALSE);
        return SHELL_FALSE;
    }
    else if (child)
    {
        // Parent process

        int status;
        // Why did I put 0 last time I used fork(2)
        waitpid(child, &status, 0);

        if (!WIFEXITED(status))
        {
            XCODE_TOENV(SHELL_FALSE);
            return SHELL_FALSE;
        }

        return WEXITSTATUS(status);
    }
    else
    {
        // Child process

        int ret = eval_ast(ast);
        // Need to exit or else we will have to exit from the main function
        // So we will execute the remainder of the ast twice
        // Which is not what we want
        exit(ret);
    }
}

int exec_ast_subshell(struct ast *ast)
{
    struct ast *sub = get_left(ast);
    int fork_res = _exec_fork(sub);
    // TODO:The exit codes might not be the correct one
    XCODE_TOENV(fork_res);
    return fork_res;
}