#include <pland/pcrt.h>
#include <knob/block.h>
#include <knob/task.h>
#include <knob/user.h>
#include "cmds.h"
#include "vars.h"

#define LINE_SIZE 4096
static char line[LINE_SIZE];

static void line_replace(const char *from) {
  const char *fi = from;
  char *ti = line;
  while (*fi) {
    if (ti == line + LINE_SIZE) {
      tell_user_sz("Line too long.\n");
      line[0] = '\0';
      return;
    }
    if (*fi != '$') {
      *ti = *fi;
      ++ti;
      ++fi;
      continue;
    }
    const char *var_start = ++fi;
    const char *var_end = var_start;
    while (*var_end != '$')
      if (!*var_end++) {
        tell_user_sz("Unterminated variable name.\n");
        line[0] = '\0';
        return;
      }
    if (ti + (var_end - var_start) >= line + LINE_SIZE) {
      tell_user_sz("Line too long.\n");
      line[0] = '\0';
      return;
    }
    struct no_null_sn vname = {
      .data = var_start,
      .length = var_end - var_start
    };
    const struct no_null_sn *vval = get_var(vname);
    if (!vval)
      vval = &vname;
    blockcpy(ti, vval->data, vval->length);
    ti += vval->length;
    fi = var_end + 1;
  }
  *ti = '\0';
}

void run_line(const char *original_line) {
  line_replace(original_line);
  if (!*line)
    return;
  const char *space;
  for (space = line; *space && (*space != ' '); ++space)
    ;
  if (blockequ(line, "source", space - line))
    source(space + 1);
  else if (blockequ(line, "set", space - line))
    set(space + 1);
  else if (blockequ(line, "echo", space - line)) {
    tell_user_sz(space + 1);
    tell_user_sz("\n");
  }
  else if (blockequ(line, "vars", space - line))
    dump_vars();
  else if (blockequ(line, "quit", space - line))
    __pcrt_quit();
  else if (blockequ(line, "help", space - line))
    tell_user_sz("Highway is a command shell for Portland OS. It includes variables and a couple\n"
                 "of pseudo-commands. Variables are addressed by surrounding with \"$\". The\n"
                 "following list shows each of the pseudo-commands.\n\n"
                 "  source FILE       run each command in FILE\n"
                 "  set VAR VALUE     set $VAR$ to VALUE\n"
                 "  echo STRING       print STRING\n"
                 "  vars              dump variables\n"
                 "  quit              exit highway\n"
                 "  help              show this\n");
  else if (!try_run_command_blocking(line)) {
    struct no_null_sn arg = {
      .data = "_path",
      .length = 5
    };
    const struct no_null_sn *path = get_var(arg);
    if (!path->length) {
      tell_user_sz("Could not run command.\n");
      return;
    }
    for (uint16_t to_i = LINE_SIZE - 1; to_i >= path->length; --to_i)
      line[to_i] = line[to_i - path->length];
    blockcpy(line, path->data, path->length);
    if (!try_run_command_blocking(line)) {
      tell_user_sz("Could not run command.\n");
      return;
    }
  }
}