#include <stdio.h>
#include <unistd.h>
#include <fcntl.h>
#include <signal.h>
#include <sys/wait.h>

#include "syntax.h"
#include "utils.h"

void execute_command_pipeline(Pipeline pipeline, int stdin_fd, int stdout_fd);


void execute_cmd(ExecutableCommand cmd, int* pgid) {

    pid_t pid = fork();

    if (pid == 0) {

        if (*pgid == -1) {
            setpgid(0, 0);
        } else {
            setpgid(0, *pgid);
        }

        dup2(cmd.stdin_fd, STDIN_FILENO);
        dup2(cmd.stdout_fd, STDOUT_FILENO);

        for (int i = 0; i < cmd.redirects.count; i++) {
            FdRedirect fd_rd = *get_from_FdRedirectVec(&cmd.redirects, i);
            dup2(fd_rd.to, fd_rd.redirected);
        }

        for (int j = 0; j < cmd.child_open_fds.count; j++) {
            int fd = *get_from_IntVec(&cmd.child_open_fds, j);
            close(fd);
        }

        signal(SIGINT,  SIG_DFL);
        signal(SIGQUIT, SIG_DFL);
        signal(SIGTSTP, SIG_DFL);
        signal(SIGTTIN, SIG_DFL);
        signal(SIGTTOU, SIG_DFL);

        execvp(cmd.args[0], cmd.args);
        exit(67);
    }

    if (*pgid == -1) {
        setpgid(pid, pid);
        *pgid = pid;
    } else {
        setpgid(pid, *pgid);
    }
}


ExecutableCommand process_pl_command(PlCommand pl_cmd) {
    StrVec arg_vec = make_StrVec(256);
    FdRedirectVec fd_redirs = make_FdRedirectVec(256);
    IntVec parent_open_fds = make_IntVec(256);
    IntVec child_open_fds = make_IntVec(256);

    int ps_pipe_fds[2];

    for (int i = 0; i < pl_cmd.args.count; i++) {
        Arg arg = *get_from_ArgVec(&pl_cmd.args, i);
        switch (arg.kind) {
            case ARG_LIT:
                push_to_StrVec(&arg_vec, arg.as.lit_str);
                break;
            case ARG_PS_IN:
                pipe(ps_pipe_fds);
                execute_command_pipeline(*(Pipeline*)arg.as.sub_pipeline, STDIN_FILENO, ps_pipe_fds[1]);
                close(ps_pipe_fds[1]);
                char pname[64];
                snprintf(pname, sizeof(pname), "/dev/fd/%d", ps_pipe_fds[0]);
                push_to_IntVec(&parent_open_fds, ps_pipe_fds[0]);
                push_to_StrVec(&arg_vec, strdup(pname));
                break;
            default:
                exit(67);
        }
    }

    for (int j = 0; j < pl_cmd.redirects.count; j++) {
        Redirect redir = *get_from_RedirectVec(&pl_cmd.redirects, j);
        FdRedirect fd_redir;
        int fd;
        switch (redir.kind) {
            case REDIR_READ:  
                fd = open(redir.as.filename, O_RDONLY, 0644);
                push_to_IntVec(&parent_open_fds, fd);
                push_to_IntVec(&child_open_fds, fd);
                fd_redir = (FdRedirect){.to = fd, .redirected = STDIN_FILENO};
                break;
            case REDIR_WRITE_APPEND:
                fd = open(redir.as.filename, O_WRONLY | O_CREAT | O_APPEND, 0644);
                push_to_IntVec(&parent_open_fds, fd);
                push_to_IntVec(&child_open_fds, fd);
                fd_redir = (FdRedirect){.to = fd, .redirected = STDOUT_FILENO};
                break;
            case REDIR_WRITE_TRUNC:
                fd = open(redir.as.filename, O_WRONLY | O_CREAT | O_TRUNC, 0644);
                push_to_IntVec(&parent_open_fds, fd);
                push_to_IntVec(&child_open_fds, fd);
                fd_redir = (FdRedirect){.to = fd, .redirected = STDOUT_FILENO};
                break;
            default:
                exit(67);
        }
        push_to_FdRedirectVec(&fd_redirs, fd_redir);
}

    char** args = malloc(sizeof(char*) * (arg_vec.count + 1));
    for (int i = 0; i < arg_vec.count; i++) {
        args[i] = *get_from_StrVec(&arg_vec, i);
    }
    args[arg_vec.count] = NULL;
    
    return (ExecutableCommand){.args = args, .redirects = fd_redirs, .parent_open_fds = parent_open_fds, .child_open_fds = child_open_fds};
}


void execute_command_pipeline(Pipeline pipeline, int stdin_fd, int stdout_fd) {
    int trunk_fd = stdin_fd;
    int pgid = -1;

    for (int i = 0; i < pipeline.count; i++) {
        PlCommand cmd = *get_from_Pipeline(&pipeline, i);
        ExecutableCommand exec_cmd = process_pl_command(cmd);

        exec_cmd.stdin_fd = trunk_fd;
        if (i > 0) {
            push_to_IntVec(&exec_cmd.parent_open_fds, trunk_fd);
            push_to_IntVec(&exec_cmd.child_open_fds, trunk_fd);
        }

        exec_cmd.stdout_fd = stdout_fd;
        
        if (cmd.conn == CONN_PIPE) {
            int pipe_fds[2];
            pipe(pipe_fds);
            exec_cmd.stdout_fd = pipe_fds[1];
            push_to_IntVec(&exec_cmd.parent_open_fds, pipe_fds[1]);
            push_to_IntVec(&exec_cmd.child_open_fds, pipe_fds[1]);
            trunk_fd = pipe_fds[0];
        }

        execute_cmd(exec_cmd, &pgid);

        for (int j = 0; j < exec_cmd.parent_open_fds.count; j++) {
            int fd = *get_from_IntVec(&exec_cmd.parent_open_fds, j);
            close(fd);
        }
    }

    tcsetpgrp(STDIN_FILENO, pgid); 
    while (waitpid(-pgid, NULL, 0) > 0); 
    tcsetpgrp(STDIN_FILENO, getpgrp());
}

void execute_pipeline_tree(PipelineTree pltree) {
    signal(SIGTTIN, SIG_IGN);
    signal(SIGTTOU, SIG_IGN);
    execute_command_pipeline(*pltree.root, STDIN_FILENO, STDOUT_FILENO); 
}