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

#include "utils.h"
#include "exec.h"
#include "preproc.h"
#include "expand.h"


void execute_command(Command 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 j = 0; j < cmd.redirs.count; j++) {
            FdRedirect fd_rd = *get_from_FdRedirectVec(&cmd.redirs, j);
            dup2(fd_rd.old_fd, fd_rd.new_fd);
        }

        for (int i = 0; i < cmd.child_close_fds.count; i++) {
            close(*get_from_IntVec(&cmd.child_close_fds, i));
        }

        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);
    }
}

Command make_command(SlotVec cmd_slots) {
    Command cmd = {
        .child_close_fds = make_IntVec(64), 
        .parent_close_fds = make_IntVec(64),
        .redirs = make_FdRedirectVec(32)
    };
    StrVec arg_strs = make_StrVec(256);
    for (int i = 0; i < cmd_slots.count; i++) {
        Slot slot = *get_from_SlotVec(&cmd_slots, i);
        switch (slot.kind) {
            case SLOT_STR:
                push_to_StrVec(&arg_strs, slot.as.str);
            default:
                exit(67);
            // TODO: other slot kinds
        }
    }
    cmd.args = malloc(sizeof(char*) * arg_strs.count);
    for (int j = 0; j < arg_strs.count; j++) {
        cmd.args[j] = *get_from_StrVec(&arg_strs, j);
    }
    return cmd;
}


void run_cmds(CommandVec cmds) {
    signal(SIGTTIN, SIG_IGN);
    signal(SIGTTOU, SIG_IGN);

    int trunk_fd = STDIN_FILENO;
    int pgid = -1;

    for (int i = 0; i < cmds.count; i++) {
        Command cmd = *get_from_CommandVec(&cmds, i);
        cmd.stdin_fd = trunk_fd;

        if (i > 0) {
            push_to_IntVec(&cmd.child_close_fds, trunk_fd);
            push_to_IntVec(&cmd.parent_close_fds, trunk_fd); 
        }

        cmd.stdout_fd = STDOUT_FILENO;
        if (cmd.term = CONN_PIPE) {
            int pipe_fds[2];
            pipe(pipe_fds);
            cmd.stdout_fd = pipe_fds[1];
            push_to_IntVec(&cmd.child_close_fds, pipe_fds[1]);
            push_to_IntVec(&cmd.parent_close_fds, pipe_fds[1]);
            trunk_fd = pipe_fds[0];
        }

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

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


CommandVec make_cmd_vec_pl(ExpandedPipeline pl) {
    CommandVec cmds = make_CommandVec(256);
    for (int i = 0; i < pl.count; i++) {
        ExpandedPipelineElement elem = *get_from_ExpandedPipeline(&pl, i);
        Command cmd = make_command(elem.cmd_slots);
        push_to_CommandVec(&cmds, cmd);
    }
}


void process_input_line(char* line, ShellState* shstate) {
    PreprocArena arena = {
        .tokens = make_TokenVec(256),
        .chunks = make_ChunkVec(256),
        .regions = make_RegionVec(256),
    };
    TokenPtrVec line_tok_ptrs = lex(line, &arena);
    Token* line_toks = malloc(sizeof(Token) * line_tok_ptrs.count);
    for (int i = 0; i < line_tok_ptrs.count; i++) {
        line_toks[i] = **get_from_TokenPtrVec(&line_tok_ptrs, i);
    }
    Pipeline pl = parse_tokstream(line_toks);
    ExpandedPipeline exp_pl = expand_pipeline(&pl, shstate);
    CommandVec cmds = make_cmd_vec_pl(exp_pl);
    run_cmds(cmds); 
    free(line_toks);
}