#include "src/lib/memory.h"
#include "src/lib/string.h"
#include "src/lib/util.h"
#include "src/user/syscall.h"

static void help(uint8_t argc, char **argv);
static void cd(uint8_t argc, char **argv);

#define PATH "/bin/"

#define PRINT_S(s) write(1, s, sizeof(s) - 1);
#define PRINT_D(s) write(1, s, string_length(s));

typedef void (*app_t)(uint8_t argc, char **argv);

typedef struct {
  const char *name;
  app_t app;
} app_entry_t;

static app_entry_t builtins[] = {
    {"help", help},
    {"cd", cd},
};

static void help(uint8_t argc, __attribute__((unused)) char **argv) {
  if (argc > 1) {
    PRINT_S("help: expects no arguments");
    return;
  }

  PRINT_S("Available commands:\n");
  for (uint64_t i = 0; i < sizeof(builtins) / sizeof(app_entry_t); i++) {
    PRINT_D(builtins[i].name);
    PRINT_S("\n");
  }
}

static void cd(uint8_t argc, char **argv) {
  if (argc != 2) {
    PRINT_S("cd: requires a single path\n");
    return;
  }

  if (chdir(argv[1]) == (uint64_t)-1) {
    PRINT_S("cd: path does not exist\n");
  }
}

static void print_prompt() {
  char path[256];
  uint8_t pl = getcwd(256, path);
  char *components[16];
  uint8_t cl = string_split(path, '/', 16, components);

  PRINT_S("[")
  PRINT_D(pl == 1 ? "/" : components[cl - 1]);
  PRINT_S("]$ ");
}

static void execute(char *command) {
  char *argv[16];
  uint8_t argc = (uint8_t)string_split(command, ' ', 16, argv);

  PRINT_S("\n");

  if (string_equal(command, "^C")) {
    print_prompt();
    return;
  }

  if (string_equal(command, "^D")) {
    exit(EXIT_CODE_OK);
  }

  uint8_t i;
  for (i = 0; i < sizeof(builtins) / sizeof(app_entry_t); i++) {
    if (string_equal(argv[0], builtins[i].name)) {
      builtins[i].app(argc, argv);
      break;
    }
  }
  if (i == sizeof(builtins) / sizeof(app_entry_t)) {
    uint64_t size = sizeof(PATH) + string_length(argv[0]) + 1;
    char *path = memory_allocate(size);
    memory_copy(PATH, sizeof(PATH), path);
    memory_copy(argv[0], size - sizeof(PATH), path + sizeof(PATH) - 1);
    uint64_t pid = spawn(path, argc, (const char **)argv);
    memory_free(path);

    if (pid == EXIT_CODE_NOT_FOUND) {
      PRINT_S("shell: program not found\n");
    } else {
      waitpid(pid);
    }
  }
  print_prompt();
}

uint64_t main() {
  PRINT_D("Welcome to FreywarOS v" VERSION "!\n\n");

  print_prompt();

  char line[256];
  uint64_t offset;

  char chunk[64];
  uint64_t received;

  while (1) {
    if ((received = read(0, sizeof(chunk), chunk))) {
      for (uint64_t i = 0; i < received; i++) {
        if (chunk[i] == '\n') {
          line[offset] = '\0';
          execute(line);
          offset = 0;
        } else if (offset < 255) {
          line[offset++] = chunk[i];
        }
      }
    }
  }

  return 0;
}