#ifndef _DEFAULT_SOURCE
#define _DEFAULT_SOURCE
#endif

#include "cst_agent.h"
#include "os_compat.h"

#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#ifdef _WIN32
#include <io.h>
#else
#include <fcntl.h>
#include <termios.h>
#include <unistd.h>
#endif

/* Config dir via os_compat: $XDG_CONFIG_HOME/cst-agent (~/.config/cst-agent)
 * or %APPDATA%\cst-agent */

static int credentials_path(char *out, size_t n) {
  char dir[OS_PATH_MAX];
  if (os_config_dir(dir, sizeof(dir)) != 0)
    return -1;
  return os_path_join(out, n, dir, "credentials");
}

static void chomp(char *s) {
  size_t len = strlen(s);
  while (len > 0 && (s[len - 1] == '\n' || s[len - 1] == '\r' ||
                     s[len - 1] == ' ' || s[len - 1] == '\t'))
    s[--len] = 0;
}

static int same_base(const char *a, const char *b) {
  size_t la = strlen(a), lb = strlen(b);
  while (la > 0 && a[la - 1] == '/')
    la--;
  while (lb > 0 && b[lb - 1] == '/')
    lb--;
  return la == lb && strncmp(a, b, la) == 0;
}

int cst_creds_load(const char *provider, char *out, size_t out_sz) {
  if (!provider || !provider[0] || !out || out_sz < 2)
    return -1;
  out[0] = 0;
  char path[OS_PATH_MAX];
  if (credentials_path(path, sizeof(path)) != 0)
    return -1;
  FILE *fp = fopen(path, "r");
  if (!fp)
    return -1;
  char want[64];
  snprintf(want, sizeof(want), "%s.api_key=", provider);
  size_t wl = strlen(want);
  /* Old single-key files ("api_key=" + "api_base=") belong to the provider
   * whose base URL matches; without a base they were MiniMax keys. */
  char legacy_key[1024] = "", legacy_base[1024] = "";
  char line[1024];
  int found = 0;
  while (fgets(line, sizeof(line), fp)) {
    chomp(line);
    if (strncmp(line, want, wl) == 0 && line[wl]) {
      snprintf(out, out_sz, "%s", line + wl);
      found = 1;
      break;
    }
    if (strncmp(line, "api_key=", 8) == 0)
      snprintf(legacy_key, sizeof(legacy_key), "%s", line + 8);
    else if (strncmp(line, "api_base=", 9) == 0)
      snprintf(legacy_base, sizeof(legacy_base), "%s", line + 9);
  }
  fclose(fp);
  if (found)
    return 0;
  if (legacy_key[0]) {
    const cst_provider_t *p = cst_provider_find(provider);
    int match = p && (legacy_base[0] ? same_base(legacy_base, p->api_base)
                                     : strcmp(provider, "minimax") == 0);
    if (match && strlen(legacy_key) < out_sz) {
      snprintf(out, out_sz, "%s", legacy_key);
      return 0;
    }
  }
  return -1;
}

int cst_creds_save(const char *provider, const char *key) {
  if (!provider || !provider[0] || !key || !key[0] || strchr(key, '\n'))
    return -1;
  char dir[OS_PATH_MAX], path[OS_PATH_MAX], tmp[OS_PATH_MAX + 8];
  if (os_config_dir(dir, sizeof(dir)) != 0 || os_mkdir_p(dir, 0700) != 0 ||
      credentials_path(path, sizeof(path)) != 0)
    return -1;
  if (snprintf(tmp, sizeof(tmp), "%s.tmp", path) >= (int)sizeof(tmp))
    return -1;

  char want[64];
  snprintf(want, sizeof(want), "%s.api_key=", provider);
  size_t wl = strlen(want);

#ifdef _WIN32
  FILE *out = fopen(tmp, "w");
#else
  /* never exists world-readable, even briefly */
  int fd = open(tmp, O_WRONLY | O_CREAT | O_TRUNC, 0600);
  FILE *out = fd >= 0 ? fdopen(fd, "w") : NULL;
  if (!out && fd >= 0)
    close(fd);
#endif
  if (!out)
    return -1;
  FILE *in = fopen(path, "r");
  if (in) {
    char line[1024];
    while (fgets(line, sizeof(line), in)) {
      if (strncmp(line, want, wl) != 0)
        fputs(line, out);
    }
    fclose(in);
  }
  fprintf(out, "%s%s\n", want, key);
  if (fclose(out) != 0) {
    remove(tmp);
    return -1;
  }
#ifdef _WIN32
  remove(path);
#endif
  if (rename(tmp, path) != 0) {
    remove(tmp);
    return -1;
  }
  (void)os_chmod_private(path);
  return 0;
}

int cst_creds_resolve(const char *provider, char *out, size_t out_sz,
                      const char **from) {
  if (from)
    *from = NULL;
  if (cst_creds_load(provider, out, out_sz) == 0 && out[0]) {
    if (from)
      *from = "saved";
    return 0;
  }
  const cst_provider_t *p = cst_provider_find(provider);
  const char *env = p ? getenv(p->key_env) : NULL;
  if (env && env[0]) {
    snprintf(out, out_sz, "%s", env);
    if (from)
      *from = p->key_env;
    return 0;
  }
  out[0] = 0;
  return -1;
}

int cst_creds_prompt_console(const char *provider, char *out, size_t out_sz) {
  if (!out || out_sz < 2)
    return -1;
  out[0] = 0;
  fprintf(stderr, "API key for %s (input hidden, saved to the config dir): ",
          provider ? provider : "?");
  fflush(stderr);
#ifndef _WIN32
  struct termios old, quiet;
  int tty = isatty(STDIN_FILENO) && tcgetattr(STDIN_FILENO, &old) == 0;
  if (tty) {
    quiet = old;
    quiet.c_lflag &= ~(tcflag_t)ECHO;
    tcsetattr(STDIN_FILENO, TCSAFLUSH, &quiet);
  }
#endif
  char *got = fgets(out, (int)out_sz, stdin);
#ifndef _WIN32
  if (tty) {
    tcsetattr(STDIN_FILENO, TCSAFLUSH, &old);
    fputc('\n', stderr);
  }
#endif
  if (!got) {
    out[0] = 0;
    return -1;
  }
  chomp(out);
  return out[0] ? 0 : -1;
}