#ifndef _POSIX_C_SOURCE
#define _POSIX_C_SOURCE 200809L
#endif

#include <errno.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <unistd.h>

typedef struct {
  char *data;
  size_t len;
  size_t cap;
} amduatd_buf_t;

static void amduatd_buf_free(amduatd_buf_t *b) {
  if (b == NULL) {
    return;
  }
  free(b->data);
  b->data = NULL;
  b->len = 0u;
  b->cap = 0u;
}

static bool amduatd_buf_reserve(amduatd_buf_t *b, size_t extra) {
  size_t need;
  size_t next;
  char *mem;
  if (b == NULL) {
    return false;
  }
  if (extra > SIZE_MAX - b->len) {
    return false;
  }
  need = b->len + extra;
  if (need <= b->cap) {
    return true;
  }
  next = b->cap == 0u ? 512u : b->cap;
  while (next < need) {
    if (next > SIZE_MAX / 2u) {
      next = need;
      break;
    }
    next *= 2u;
  }
  mem = (char *)realloc(b->data, next);
  if (mem == NULL) {
    return false;
  }
  b->data = mem;
  b->cap = next;
  return true;
}

static bool amduatd_buf_append(amduatd_buf_t *b, const char *s, size_t n) {
  if (b == NULL) {
    return false;
  }
  if (n == 0u) {
    return true;
  }
  if (s == NULL) {
    return false;
  }
  if (!amduatd_buf_reserve(b, n)) {
    return false;
  }
  memcpy(b->data + b->len, s, n);
  b->len += n;
  return true;
}

static bool amduatd_buf_append_cstr(amduatd_buf_t *b, const char *s) {
  return amduatd_buf_append(b, s, s != NULL ? strlen(s) : 0u);
}

static void amduatd_usage(const char *prog) {
  fprintf(stderr,
          "usage: %s --sock PATH --method METHOD --path PATH "
          "[--header \"K: V\"]... [--data STRING|--data-file PATH] "
          "[--allow-status]\n",
          prog);
}

static bool amduatd_read_file(const char *path, uint8_t **out_data,
                              size_t *out_len) {
  FILE *fp;
  long size;
  uint8_t *buf;
  if (out_data == NULL || out_len == NULL || path == NULL) {
    return false;
  }
  *out_data = NULL;
  *out_len = 0u;
  fp = fopen(path, "rb");
  if (fp == NULL) {
    return false;
  }
  if (fseek(fp, 0, SEEK_END) != 0) {
    fclose(fp);
    return false;
  }
  size = ftell(fp);
  if (size < 0) {
    fclose(fp);
    return false;
  }
  if (fseek(fp, 0, SEEK_SET) != 0) {
    fclose(fp);
    return false;
  }
  buf = (uint8_t *)malloc((size_t)size);
  if (buf == NULL) {
    fclose(fp);
    return false;
  }
  if (size != 0 &&
      fread(buf, 1u, (size_t)size, fp) != (size_t)size) {
    free(buf);
    fclose(fp);
    return false;
  }
  fclose(fp);
  *out_data = buf;
  *out_len = (size_t)size;
  return true;
}

static int amduatd_parse_status(const char *line) {
  const char *p;
  char *end = NULL;
  long code;
  if (line == NULL) {
    return -1;
  }
  p = strchr(line, ' ');
  if (p == NULL) {
    return -1;
  }
  while (*p == ' ') {
    p++;
  }
  errno = 0;
  code = strtol(p, &end, 10);
  if (errno != 0 || end == p || code < 0 || code > 999) {
    return -1;
  }
  return (int)code;
}

int main(int argc, char **argv) {
  const char *sock_path = NULL;
  const char *method = NULL;
  const char *path = NULL;
  bool allow_status = false;
  char **headers = NULL;
  size_t header_count = 0u;
  uint8_t *body = NULL;
  size_t body_len = 0u;
  int fd = -1;
  struct sockaddr_un addr;
  amduatd_buf_t req;
  amduatd_buf_t resp;
  ssize_t nread;
  int status;
  char *header_end;
  size_t body_offset;
  size_t i;

  memset(&req, 0, sizeof(req));
  memset(&resp, 0, sizeof(resp));

  for (i = 1; i < (size_t)argc; ++i) {
    const char *arg = argv[i];
    if (strcmp(arg, "--sock") == 0 && i + 1 < (size_t)argc) {
      sock_path = argv[++i];
    } else if (strcmp(arg, "--method") == 0 && i + 1 < (size_t)argc) {
      method = argv[++i];
    } else if (strcmp(arg, "--path") == 0 && i + 1 < (size_t)argc) {
      path = argv[++i];
    } else if (strcmp(arg, "--header") == 0 && i + 1 < (size_t)argc) {
      char **next = (char **)realloc(headers,
                                     (header_count + 1u) * sizeof(*headers));
      if (next == NULL) {
        fprintf(stderr, "oom\n");
        goto fail;
      }
      headers = next;
      headers[header_count++] = argv[++i];
    } else if (strcmp(arg, "--data") == 0 && i + 1 < (size_t)argc) {
      const char *data = argv[++i];
      body_len = strlen(data);
      if (body_len == 0u) {
        body = NULL;
      } else {
        body = (uint8_t *)malloc(body_len);
        if (body == NULL) {
          fprintf(stderr, "oom\n");
          goto fail;
        }
        memcpy(body, data, body_len);
      }
    } else if (strcmp(arg, "--data-file") == 0 && i + 1 < (size_t)argc) {
      if (!amduatd_read_file(argv[++i], &body, &body_len)) {
        fprintf(stderr, "failed to read data file\n");
        goto fail;
      }
    } else if (strcmp(arg, "--allow-status") == 0) {
      allow_status = true;
    } else {
      amduatd_usage(argv[0]);
      goto fail;
    }
  }

  if (sock_path == NULL || method == NULL || path == NULL) {
    amduatd_usage(argv[0]);
    goto fail;
  }

  fd = socket(AF_UNIX, SOCK_STREAM, 0);
  if (fd < 0) {
    perror("socket");
    goto fail;
  }

  memset(&addr, 0, sizeof(addr));
  addr.sun_family = AF_UNIX;
  if (strlen(sock_path) >= sizeof(addr.sun_path)) {
    fprintf(stderr, "socket path too long\n");
    goto fail;
  }
  strncpy(addr.sun_path, sock_path, sizeof(addr.sun_path) - 1u);

  if (connect(fd, (struct sockaddr *)&addr, sizeof(addr)) != 0) {
    perror("connect");
    goto fail;
  }

  if (!amduatd_buf_append_cstr(&req, method) ||
      !amduatd_buf_append_cstr(&req, " ") ||
      !amduatd_buf_append_cstr(&req, path) ||
      !amduatd_buf_append_cstr(&req, " HTTP/1.1\r\n") ||
      !amduatd_buf_append_cstr(&req, "Host: localhost\r\n") ||
      !amduatd_buf_append_cstr(&req, "Connection: close\r\n")) {
    fprintf(stderr, "oom\n");
    goto fail;
  }
  for (i = 0; i < header_count; ++i) {
    if (!amduatd_buf_append_cstr(&req, headers[i]) ||
        !amduatd_buf_append_cstr(&req, "\r\n")) {
      fprintf(stderr, "oom\n");
      goto fail;
    }
  }
  if (body != NULL) {
    char len_buf[64];
    int len;
    len = snprintf(len_buf, sizeof(len_buf), "Content-Length: %zu\r\n",
                   body_len);
    if (len < 0 || (size_t)len >= sizeof(len_buf) ||
        !amduatd_buf_append(&req, len_buf, (size_t)len)) {
      fprintf(stderr, "oom\n");
      goto fail;
    }
  }
  if (!amduatd_buf_append_cstr(&req, "\r\n")) {
    fprintf(stderr, "oom\n");
    goto fail;
  }

  {
    size_t off = 0u;
    while (off < req.len) {
      ssize_t n = write(fd, req.data + off, req.len - off);
      if (n <= 0) {
        perror("write");
        goto fail;
      }
      off += (size_t)n;
    }
  }
  if (body != NULL && body_len != 0u) {
    size_t off = 0u;
    while (off < body_len) {
      ssize_t n = write(fd, body + off, body_len - off);
      if (n <= 0) {
        perror("write");
        goto fail;
      }
      off += (size_t)n;
    }
  }

  while (true) {
    char tmp[4096];
    nread = read(fd, tmp, sizeof(tmp));
    if (nread < 0) {
      perror("read");
      goto fail;
    }
    if (nread == 0) {
      break;
    }
    if (!amduatd_buf_append(&resp, tmp, (size_t)nread)) {
      fprintf(stderr, "oom\n");
      goto fail;
    }
  }

  if (resp.len == 0u) {
    fprintf(stderr, "empty response\n");
    goto fail;
  }
  if (!amduatd_buf_append(&resp, "\0", 1u)) {
    fprintf(stderr, "oom\n");
    goto fail;
  }

  {
    char *line_end = strstr(resp.data, "\r\n");
    if (line_end == NULL) {
      fprintf(stderr, "invalid response\n");
      goto fail;
    }
    *line_end = '\0';
    status = amduatd_parse_status(resp.data);
    *line_end = '\r';
    if (status < 0) {
      fprintf(stderr, "invalid status\n");
      goto fail;
    }
  }

  header_end = strstr(resp.data, "\r\n\r\n");
  if (header_end == NULL) {
    body_offset = resp.len;
  } else {
    body_offset = (size_t)(header_end - resp.data) + 4u;
  }

  if (body_offset < resp.len) {
    size_t out_len = resp.len - body_offset;
    if (resp.len > 0u && resp.data[resp.len - 1u] == '\0') {
      if (out_len > 0u) {
        out_len -= 1u;
      }
    }
    if (out_len > 0u) {
      fwrite(resp.data + body_offset, 1u, out_len, stdout);
    }
  }
  fflush(stdout);

  amduatd_buf_free(&req);
  amduatd_buf_free(&resp);
  free(body);
  free(headers);
  if (fd >= 0) {
    close(fd);
  }

  if (!allow_status && (status < 200 || status >= 300)) {
    return 1;
  }
  return 0;

fail:
  amduatd_buf_free(&req);
  amduatd_buf_free(&resp);
  free(body);
  free(headers);
  if (fd >= 0) {
    close(fd);
  }
  return 1;
}