/*
 * Mr. 4th Dimention - Allen Webster
 *
 * 30.06.2017
 *
 * General unix functions
 *
 */

// TOP

#include <sys/mman.h>

#include <sys/types.h>
#include <sys/stat.h>
#include <sys/epoll.h>
#include <sys/wait.h>

#include <fcntl.h>
#include <unistd.h>
#include <dirent.h>
#include <alloca.h>
#include <errno.h>
#include <time.h>

#include <stdlib.h>
#if defined(USE_LOG)
# include <stdio.h>
#endif

//
// Unix Structs / Enums
//

struct Unix_Vars{
    b32 do_logging;
    
    int epoll;
};

static Unix_Vars unixvars;

enum{
    UNIX_4ED_EVENT_CLI = (UINT64_C(1) << 32),
};

//
// Vars Init
//

internal void
unixvars_init(){
    unixvars.epoll = epoll_create(16);
}

//
// 4ed Path
//

internal
Sys_Get_4ed_Path_Sig(system_get_4ed_path){
    ssize_t size = readlink("/proc/self/exe", out, capacity - 1);
    if (size != -1 && size < capacity - 1){
        String str = make_string(out, size);
        remove_last_folder(&str);
        terminate_with_null(&str);
        size = str.size;
    }
    else{
        size = 0;
    }
    return(size);
}

//
// Logging
//

internal
Sys_Log_Sig(system_log){
    if (unixvars.do_logging){
        i32 fd = open("4coder_log.txt", O_WRONLY | O_CREAT, 00640);
        if (fd >= 0){
            do{
                ssize_t written = write(fd, message, length);
                if (written != -1){
                    length -= written;
                    message += written;
                }
            } while(length > 0);
            close(fd);
        }
    }
}

//
// Shared system functions (system_shared.h)
//

internal
Sys_File_Can_Be_Made_Sig(system_file_can_be_made){
    b32 result = access((char*)filename, W_OK) == 0;
    LOGF("%s = %d", filename, result);
    return(result);
}

//
// Memory
//

internal
Sys_Memory_Allocate_Sig(system_memory_allocate){
    // NOTE(allen): This must return the exact base of the vpage.
    // We will count on the user to keep track of size themselves.
    void *result = mmap(0, size, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
    if(result == MAP_FAILED){
        LOG("mmap failed\n");
        result = NULL;
    }
    return(result);
}

internal 
Sys_Memory_Set_Protection_Sig(system_memory_set_protection){
    bool32 result = true;
    
    int protect = 0;
    switch (flags & 0x7){
        case 0: protect = PROT_NONE; break;
        
        case MemProtect_Read:
        protect = PROT_READ; break;
        
        case MemProtect_Write:
        case MemProtect_Read|MemProtect_Write:
        protect = PROT_READ | PROT_WRITE; break;
        
        case MemProtect_Execute:
        protect = PROT_EXEC; break;
        
        case MemProtect_Execute|MemProtect_Read:
        protect = PROT_READ | PROT_EXEC; break;
        
        // NOTE(inso): some W^X protection things might be unhappy about this one
        case MemProtect_Execute|MemProtect_Write:
        case MemProtect_Execute|MemProtect_Write|MemProtect_Read:
        protect = PROT_READ | PROT_WRITE | PROT_EXEC; break;
    }
    
    if(mprotect(ptr, size, protect) == -1){
        result = 0;
        LOG("mprotect");
    }
    
    return(result);
}

internal
Sys_Memory_Free_Sig(system_memory_free){
    // NOTE(allen): This must take the exact base of the vpage.
    munmap(ptr, size);
}

//
// Files
//

internal
Sys_Set_File_List_Sig(system_set_file_list){
    if (directory == 0){
        system_memory_free(file_list->block, file_list->block_size);
        file_list->block = 0;
        file_list->block_size = 0;
        file_list->infos = 0;
        file_list->count = 0;
        return;
    }
    
    LOGF("%s", directory);
    
    DIR *d = opendir(directory);
    if (d != 0){
        if (canon_directory_out != 0){
            u32 length = copy_fast_unsafe_cc(canon_directory_out, directory);
            if (canon_directory_out[length-1] != '/'){
                canon_directory_out[length++] = '/';
            }
            canon_directory_out[length] = 0;
            *canon_directory_size_out = length;
        }
        
        i32 character_count = 0;
        i32 file_count = 0;
        for (struct dirent *entry = readdir(d);
             entry != 0;
             entry = readdir(d)){
            char *fname = entry->d_name;
            if (match_cc(fname, ".") || match_cc(fname, "..")){
                continue;
            }
            ++file_count;
            i32 size = 0;
            for (; fname[size]; ++size);
            character_count += size + 1;
        }
        
        i32 required_size = character_count + file_count * sizeof(File_Info);
        if (file_list->block_size < required_size){
            system_memory_free(file_list->block, file_list->block_size);
            file_list->block = system_memory_allocate(required_size);
            file_list->block_size = required_size;
        }
        
        file_list->infos = (File_Info*)file_list->block;
        char *cursor = (char*)(file_list->infos + file_count);
        
        if (file_list->block != 0){
            rewinddir(d);
            File_Info *info_ptr = file_list->infos;
            for (struct dirent *entry = readdir(d);
                 entry != 0;
                 entry = readdir(d)){
                char *fname = entry->d_name;
                if (match_cc(fname, ".") || match_cc(fname, "..")){
                    continue;
                }
                char *cursor_start = cursor;
                i32 length = copy_fast_unsafe_cc(cursor_start, fname);
                cursor += length;
                
                if(entry->d_type == DT_LNK){
                    struct stat st;
                    if(stat(entry->d_name, &st) != -1){
                        info_ptr->folder = S_ISDIR(st.st_mode);
                    }
                    else{
                        info_ptr->folder = 0;
                    }
                }
                else{
                    info_ptr->folder = (entry->d_type == DT_DIR);
                }
                
                info_ptr->filename = cursor_start;
                info_ptr->filename_len = length;
                *cursor++ = 0;
                ++info_ptr;
            }
        }
        
        file_list->count = file_count;
        
        closedir(d);
    }
    else{
        system_memory_free(file_list->block, file_list->block_size);
        file_list->block = 0;
        file_list->block_size = 0;
        file_list->infos = 0;
        file_list->count = 0;
    }
}

internal
Sys_Get_Canonical_Sig(system_get_canonical){
    char* path = (char*) alloca(len + 1);
    char* write_p = path;
    const char* read_p = filename;
    
    // return 0 for relative paths (e.g. cmdline args)
    if(len > 0 && filename[0] != '/'){
        return 0;
    }
    
    if (max == 0){
        return 0;
    }
    
    max -= 1;
    
    while(read_p < filename + len){
        if(read_p == filename || read_p[0] == '/'){
            if(read_p[1] == '/'){
                ++read_p;
            } else if(read_p[1] == '.'){
                if(read_p[2] == '/' || !read_p[2]){
                    read_p += 2;
                } else if(read_p[2] == '.' && (read_p[3] == '/' || !read_p[3])){
                    while(write_p > path && *--write_p != '/');
                    read_p += 3;
                } else {
                    *write_p++ = *read_p++;
                }
            } else {
                *write_p++ = *read_p++;
            }
        } else {
            *write_p++ = *read_p++;
        }
    }
    if(write_p == path) *write_p++ = '/';
    
    if(max >= (write_p - path)){
        memcpy(buffer, path, write_p - path);
    } else {
        write_p = path;
    }
    
#if FRED_INTERNAL
    if(len != (write_p - path) || memcmp(filename, path, len) != 0){
        LOGF("[%.*s] -> [%.*s]", len, filename, (int)(write_p - path), path);
    }
#endif
    
    u32 length = (i32)(write_p - path);
    buffer[length] = 0;
    return(length);
}

internal
Sys_Load_Handle_Sig(system_load_handle){
    b32 result = 0;
    
    int fd = open(filename, O_RDONLY);
    if(fd == -1){
        LOG("open");
    } else {
        *(int*)handle_out = fd;
        result = 1;
    }
    
    return result;
}

internal
Sys_Load_Size_Sig(system_load_size){
    u32 result = 0;
    
    int fd = *(int*)&handle;
    struct stat st;
    
    if(fstat(fd, &st) == -1){
        LOG("fstat");
    }
    else{
        result = st.st_size;
    }
    
    return result;
}

internal
Sys_Load_File_Sig(system_load_file){
    int fd = *(int*)&handle;
    
    do{
        ssize_t n = read(fd, buffer, size);
        if(n == -1){
            if(errno != EINTR){
                LOG("read");
                break;
            }
        }
        else{
            size -= n;
            buffer += n;
        }
    } while(size);
    
    return size == 0;
}

internal
Sys_Load_Close_Sig(system_load_close){
    b32 result = 1;
    
    int fd = *(int*)&handle;
    if(close(fd) == -1){
        LOG("close");
        result = 0;
    }
    
    return result;
}

internal
Sys_Save_File_Sig(system_save_file){
    int fd = open(filename, O_WRONLY | O_TRUNC | O_CREAT, 00640);
    LOGF("%s %d", filename, size);
    if(fd < 0){
        LOGF("system_save_file: open '%s': %s\n", filename, strerror(errno));
    }
    else{
        do {
            ssize_t written = write(fd, buffer, size);
            if(written == -1){
                if(errno != EINTR){
                    LOG("system_save_file: write");
                    break;
                }
            } else {
                size -= written;
                buffer += written;
            }
        } while(size);
        close(fd);
    }
    
    return (size == 0);
}

//
// File System
//

internal
Sys_File_Exists_Sig(system_file_exists){
    int result = 0;
    char buff[PATH_MAX] = {};
    
    if (len + 1 > PATH_MAX){
        LOG("system_directory_has_file: path too long\n");
    }
    else{
        memcpy(buff, filename, len);
        buff[len] = 0;
        struct stat st;
        result = stat(buff, &st) == 0 && S_ISREG(st.st_mode);
    }
    
    LOGF("%s: %d", buff, result);
    
    return(result);
}

internal
Sys_Directory_CD_Sig(system_directory_cd){
    String directory = make_string_cap(dir, *len, cap);
    b32 result = false;
    
    if (rel_path[0] != 0){
        if (rel_path[0] == '.' && rel_path[1] == 0){
            result = true;
        }
        else if (rel_path[0] == '.' && rel_path[1] == '.' && rel_path[2] == 0){
            result = remove_last_folder(&directory);
            terminate_with_null(&directory);
        }
        else{
            if (directory.size + rel_len + 1 > directory.memory_size){
                i32 old_size = directory.size;
                append_partial_sc(&directory, rel_path);
                append_s_char(&directory, '/');
                terminate_with_null(&directory);
                
                struct stat st;
                if (stat(directory.str, &st) == 0 && S_ISDIR(st.st_mode)){
                    result = true;
                }
                else{
                    directory.size = old_size;
                }
            }
        }
    }
    
    *len = directory.size;
    LOGF("%.*s: %d", directory.size, directory.str, result);
    
    return(result);
}

//
// Time
//

internal
Sys_Now_Time_Sig(system_now_time){
    struct timespec spec;
    clock_gettime(CLOCK_REALTIME, &spec);
    u64 result = (spec.tv_sec * UINT64_C(1000000)) + (spec.tv_nsec / UINT64_C(1000));
    return(result);
}

//
// CLI
//

internal
Sys_CLI_Call_Sig(system_cli_call){
    LOGF("%s %s", path, script_name);
    
    int pipe_fds[2];
    if (pipe(pipe_fds) == -1){
        perror("system_cli_call: pipe");
        return 0;
    }
    
    pid_t child_pid = fork();
    if (child_pid == -1){
        perror("system_cli_call: fork");
        return 0;
    }
    
    enum { PIPE_FD_READ, PIPE_FD_WRITE };
    
    // child
    if (child_pid == 0){
        close(pipe_fds[PIPE_FD_READ]);
        dup2(pipe_fds[PIPE_FD_WRITE], STDOUT_FILENO);
        dup2(pipe_fds[PIPE_FD_WRITE], STDERR_FILENO);
        
        if (chdir(path) == -1){
            LOG("system_cli_call: chdir");
            exit(1);
        }
        
        char* argv[] = { "sh", "-c", script_name, NULL };
        
        if (execv("/bin/sh", argv) == -1){
            LOG("system_cli_call: execv");
        }
        exit(1);
    }
    else{
        close(pipe_fds[PIPE_FD_WRITE]);
        
        *(pid_t*)&cli_out->proc = child_pid;
        *(int*)&cli_out->out_read = pipe_fds[PIPE_FD_READ];
        *(int*)&cli_out->out_write = pipe_fds[PIPE_FD_WRITE];
        
        struct epoll_event e = {};
        e.events = EPOLLIN | EPOLLET;
        e.data.u64 = UNIX_4ED_EVENT_CLI;
        epoll_ctl(unixvars.epoll, EPOLL_CTL_ADD, pipe_fds[PIPE_FD_READ], &e);
    }
    
    return(1);
}

internal
Sys_CLI_Begin_Update_Sig(system_cli_begin_update){
    // NOTE(inso): I don't think anything needs to be done here.
}

internal
Sys_CLI_Update_Step_Sig(system_cli_update_step){
    int pipe_read_fd = *(int*)&cli->out_read;
    
    fd_set fds;
    FD_ZERO(&fds);
    FD_SET(pipe_read_fd, &fds);
    
    struct timeval tv = {};
    
    size_t space_left = max;
    char* ptr = dest;
    
    while(space_left > 0 && select(pipe_read_fd + 1, &fds, NULL, NULL, &tv) == 1){
        ssize_t num = read(pipe_read_fd, ptr, space_left);
        if (num == -1){
            perror("system_cli_update_step: read");
        }
        else if (num == 0){
            // NOTE(inso): EOF
            break;
        }
        else{
            ptr += num;
            space_left -= num;
        }
    }
    
    *amount = (ptr - dest);
    return (ptr - dest) > 0;
}

internal
Sys_CLI_End_Update_Sig(system_cli_end_update){
    pid_t pid = *(pid_t*)&cli->proc;
    b32 close_me = false;
    
    int status;
    if (pid && waitpid(pid, &status, WNOHANG) > 0){
        close_me = true;
        
        cli->exit = WEXITSTATUS(status);
        
        struct epoll_event e = {};
        epoll_ctl(unixvars.epoll, EPOLL_CTL_DEL, *(int*)&cli->out_read, &e);
        
        close(*(int*)&cli->out_read);
        close(*(int*)&cli->out_write);
    }
    
    return(close_me);
}

// BOTTOM