#if 0
/*─────────────────────────────────────────────────────────────────╗
│ To the extent possible under law, Justine Tunney has waived      │
│ all copyright and related or neighboring rights to this file,    │
│ as it is written in the following disclaimers:                   │
│   • http://unlicense.org/                                        │
│   • http://creativecommons.org/publicdomain/zero/1.0/            │
╚─────────────────────────────────────────────────────────────────*/
#endif
#include "libc/assert.h"
#include "libc/calls/calls.h"
#include "libc/calls/struct/iovec.h"
#include "libc/calls/struct/timeval.h"
#include "libc/errno.h"
#include "libc/fmt/itoa.h"
#include "libc/fmt/magnumstrs.internal.h"
#include "libc/macros.h"
#include "libc/mem/gc.h"
#include "libc/mem/mem.h"
#include "libc/runtime/runtime.h"
#include "libc/sock/goodsocket.internal.h"
#include "libc/sock/sock.h"
#include "libc/stdio/append.h"
#include "libc/stdio/rand.h"
#include "libc/stdio/stdio.h"
#include "libc/str/slice.h"
#include "libc/str/str.h"
#include "libc/sysv/consts/af.h"
#include "libc/sysv/consts/ipproto.h"
#include "libc/sysv/consts/sig.h"
#include "libc/sysv/consts/sock.h"
#include "net/http/http.h"
#include "net/http/url.h"
#include "net/https/https.h"
#include "third_party/getopt/getopt.internal.h"
#include "third_party/mbedtls/ctr_drbg.h"
#include "third_party/mbedtls/debug.h"
#include "third_party/mbedtls/error.h"
#include "third_party/mbedtls/iana.h"
#include "third_party/mbedtls/net_sockets.h"
#include "third_party/mbedtls/ssl.h"
#include "third_party/mbedtls/x509.h"
#include "third_party/musl/netdb.h"

/**
 * @fileoverview Downloads HTTP URL to stdout.
 */

#define HasHeader(H)    (!!msg.headers[H].a)
#define HeaderData(H)   (p + msg.headers[H].a)
#define HeaderLength(H) (msg.headers[H].b - msg.headers[H].a)
#define HeaderEqualCase(H, S) \
  SlicesEqualCase(S, strlen(S), HeaderData(H), HeaderLength(H))

static int sock;
static int outfd;
static const char *prog;
static const char *outpath;

static wontreturn void PrintUsage(int fd, int rc) {
  tinyprint(fd, "usage: ", prog, " [-iksvV] URL\n", NULL);
  exit(rc);
}

static const char *DescribeErrno(void) {
  const char *reason;
  if (!(reason = _strerdoc(errno)))
    reason = "Unknown error";
  return reason;
}

static int GetSslEntropy(void *c, unsigned char *p, size_t n) {
  if (getrandom(p, n, 0) != n) {
    perror("getrandom");
    exit(1);
  }
  return 0;
}

static void OnSslDebug(void *ctx, int level, const char *file, int line,
                       const char *message) {
  char sline[12];
  char slevel[12];
  FormatInt32(sline, line);
  FormatInt32(slevel, level);
  tinyprint(2, file, ":", sline, ": (", slevel, ") ", message, "\n", NULL);
}

static void WriteOutput(const void *p, size_t n) {
  if (!outfd) {
    if (outpath) {
      if ((outfd = creat(outpath, 0644)) <= 0) {
        perror(outpath);
        exit(1);
      }
    } else {
      outfd = 1;
      outpath = "<stdout>";
    }
  }
  ssize_t rc;
  for (size_t i = 0; i < n; i += rc) {
    rc = write(outfd, p, n);
    if (rc <= 0) {
      perror(outpath);
      exit(1);
    }
  }
}

static int TlsSend(void *c, const unsigned char *p, size_t n) {
  int rc;
  if ((rc = write(*(int *)c, p, n)) == -1) {
    perror("TlsSend");
    exit(1);
  }
  return rc;
}

static int TlsRecv(void *c, unsigned char *p, size_t n, uint32_t o) {
  int r;
  struct iovec v[2];
  static unsigned a, b;
  static unsigned char t[4096];
  if (a < b) {
    r = MIN(n, b - a);
    memcpy(p, t + a, r);
    if ((a += r) == b) {
      a = b = 0;
    }
    return r;
  }
  v[0].iov_base = p;
  v[0].iov_len = n;
  v[1].iov_base = t;
  v[1].iov_len = sizeof(t);
  if ((r = readv(*(int *)c, v, 2)) == -1) {
    perror("TlsRecv");
    exit(1);
  }
  if (r > n) {
    b = r - n;
  }
  return MIN(n, r);
}

int _curl(int argc, char *argv[]) {

  if (!NoDebug()) {
    ShowCrashReports();
  }

  prog = argv[0];
  if (!prog) {
    prog = "curl";
  }

  /*
   * Read flags.
   */
  int opt;
  struct Headers {
    size_t n;
    char **p;
  } headers = {0};
  uint64_t method = 0;
  int authmode = MBEDTLS_SSL_VERIFY_REQUIRED;
  int ciphersuite = MBEDTLS_SSL_PRESET_SUITEC;
  bool includeheaders = false;
  const char *postdata = NULL;
  const char *agent = "hurl/1.o (https://github.com/jart/cosmopolitan)";
  while ((opt = getopt(argc, argv, "qiksvBVIX:H:A:d:o:")) != -1) {
    switch (opt) {
      case 's':
      case 'q':
        break;
      case 'o':
        outpath = optarg;
        break;
      case 'i':
        includeheaders = true;
        break;
      case 'I':
        method = kHttpHead;
        break;
      case 'A':
        agent = optarg;
        break;
      case 'H':
        headers.p = realloc(headers.p, ++headers.n * sizeof(*headers.p));
        headers.p[headers.n - 1] = optarg;
        break;
      case 'd':
        postdata = optarg;
        break;
      case 'X':
        if (!(method = ParseHttpMethod(optarg, -1))) {
          tinyprint(2, prog, ": bad http method: ", optarg, "\n", NULL);
          exit(1);
        }
        break;
      case 'V':
        ++mbedtls_debug_threshold;
        break;
      case 'k':
        authmode = MBEDTLS_SSL_VERIFY_NONE;
        break;
      case 'B':
        ciphersuite = MBEDTLS_SSL_PRESET_SUITEB;
        break;
      case 'h':
        PrintUsage(1, 0);
      default:
        PrintUsage(2, 1);
    }
  }

  /*
   * Get argument.
   */
  const char *urlarg;
  if (optind == argc) {
    tinyprint(2, prog, ": missing url\n", NULL);
    PrintUsage(2, 1);
  }
  urlarg = argv[optind];

  /*
   * Parse URL.
   */
  struct Url url;
  char *host, *port;
  bool usessl = false;
  gc(ParseUrl(urlarg, -1, &url, kUrlPlus));
  gc(url.params.p);
  if (url.scheme.n) {
    if (url.scheme.n == 5 && !memcasecmp(url.scheme.p, "https", 5)) {
      usessl = true;
    } else if (!(url.scheme.n == 4 && !memcasecmp(url.scheme.p, "http", 4))) {
      tinyprint(2, prog, ": not an http/https url: ", urlarg, "\n", NULL);
      exit(1);
    }
  }
  if (url.host.n) {
    host = gc(strndup(url.host.p, url.host.n));
    if (url.port.n) {
      port = gc(strndup(url.port.p, url.port.n));
    } else {
      port = usessl ? "443" : "80";
    }
  } else {
    host = "127.0.0.1";
    port = usessl ? "443" : "80";
  }
  if (!IsAcceptableHost(host, -1)) {
    tinyprint(2, prog, ": invalid host: ", urlarg, "\n", NULL);
    exit(1);
  }
  url.fragment.p = 0, url.fragment.n = 0;
  url.scheme.p = 0, url.scheme.n = 0;
  url.user.p = 0, url.user.n = 0;
  url.pass.p = 0, url.pass.n = 0;
  url.host.p = 0, url.host.n = 0;
  url.port.p = 0, url.port.n = 0;
  if (!url.path.n || url.path.p[0] != '/') {
    char *p = gc(malloc(1 + url.path.n));
    mempcpy(mempcpy(p, "/", 1), url.path.p, url.path.n);
    url.path.p = p;
    ++url.path.n;
  }

  /*
   * Create HTTP message.
   */
  if (!method) {
    if (postdata) {
      method = kHttpPost;
    } else {
      method = kHttpGet;
    }
  }

  char *request = 0;
  char methodstr[9] = {0};
  WRITE64LE(methodstr, method);
  appendf(&request,
          "%s %s HTTP/1.1\r\n"
          "Connection: close\r\n"
          "User-Agent: %s\r\n",
          methodstr, gc(EncodeUrl(&url, 0)), agent);

  bool senthost = false;
  bool sentcontenttype = false;
  bool sentcontentlength = false;
  for (int i = 0; i < headers.n; ++i) {
    appends(&request, headers.p[i]);
    appends(&request, "\r\n");
    if (!strncasecmp("Host:", headers.p[i], 5)) {
      senthost = true;
    } else if (!strncasecmp("Content-Type:", headers.p[i], 13)) {
      sentcontenttype = true;
    } else if (!strncasecmp("Content-Length:", headers.p[i], 15)) {
      sentcontentlength = true;
    }
  }
  if (!senthost) {
    appends(&request, "Host: ");
    appends(&request, host);
    appendw(&request, ':');
    appends(&request, port);
    appends(&request, "\r\n");
  }
  if (postdata) {
    if (!sentcontenttype) {
      appends(&request, "Content-Type: application/x-www-form-urlencoded\r\n");
    }
    if (!sentcontentlength) {
      char ibuf[21];
      FormatUint64(ibuf, strlen(postdata));
      appends(&request, "Content-Length: ");
      appends(&request, ibuf);
      appends(&request, "\r\n");
    }
  }
  appends(&request, "\r\n");
  if (postdata) {
    appends(&request, postdata);
  }

  /*
   * Perform DNS lookup.
   */
  struct addrinfo *addr;
  struct addrinfo hints = {.ai_family = AF_UNSPEC,
                           .ai_socktype = SOCK_STREAM,
                           .ai_protocol = IPPROTO_TCP,
                           .ai_flags = AI_NUMERICSERV};
  if (getaddrinfo(host, port, &hints, &addr) != 0) {
    tinyprint(2, prog, ": could not resolve host: ", host, "\n", NULL);
    exit(1);
  }

  /*
   * Connect to server.
   */
  int ret;
  if ((sock = GoodSocket(addr->ai_family, addr->ai_socktype, addr->ai_protocol,
                         false, &(struct timeval){-60})) == -1) {
    perror("socket");
    exit(1);
  }
  if (connect(sock, addr->ai_addr, addr->ai_addrlen)) {
    tinyprint(2, prog, ": failed to connect to ", host, " port ", port, ": ",
              DescribeErrno(), "\n", NULL);
    exit(1);
  }
  freeaddrinfo(addr);

  /*
   * Setup crypto.
   */
  mbedtls_ssl_config conf;
  mbedtls_ssl_context ssl;
  mbedtls_ctr_drbg_context drbg;
  if (usessl) {
    mbedtls_ssl_init(&ssl);
    mbedtls_ctr_drbg_init(&drbg);
    mbedtls_ssl_config_init(&conf);
    unassert(!mbedtls_ctr_drbg_seed(&drbg, GetSslEntropy, 0, "justine", 7));
    unassert(!mbedtls_ssl_config_defaults(&conf, MBEDTLS_SSL_IS_CLIENT,
                                          MBEDTLS_SSL_TRANSPORT_STREAM,
                                          ciphersuite));
    mbedtls_ssl_conf_authmode(&conf, authmode);
    mbedtls_ssl_conf_ca_chain(&conf, GetSslRoots(), 0);
    mbedtls_ssl_conf_rng(&conf, mbedtls_ctr_drbg_random, &drbg);
#ifndef NDEBUG
    mbedtls_ssl_conf_dbg(&conf, OnSslDebug, 0);
#endif
    unassert(!mbedtls_ssl_setup(&ssl, &conf));
    unassert(!mbedtls_ssl_set_hostname(&ssl, host));
    mbedtls_ssl_set_bio(&ssl, &sock, TlsSend, 0, TlsRecv);
    if ((ret = mbedtls_ssl_handshake(&ssl))) {
      tinyprint(2, prog, ": ssl negotiation with ", host,
                " failed: ", DescribeSslClientHandshakeError(&ssl, ret), "\n",
                NULL);
      exit(1);
    }
  }

  /*
   * Send HTTP Message.
   */
  ssize_t rc;
  size_t i, n;
  n = appendz(request).i;
  for (i = 0; i < n; i += rc) {
    if (usessl) {
      rc = mbedtls_ssl_write(&ssl, request + i, n - i);
      if (rc <= 0) {
        tinyprint(2, prog, ": ssl send failed: ", DescribeMbedtlsErrorCode(rc),
                  "\n", NULL);
        exit(1);
      }
    } else {
      rc = write(sock, request + i, n - i);
      if (rc <= 0) {
        tinyprint(2, prog, ": send failed: ", DescribeErrno(), "\n", NULL);
        exit(1);
      }
    }
  }

  /*
   * Handle response.
   */
  int t;
  char *p;
  struct HttpMessage msg;
  struct HttpUnchunker u;
  size_t g, hdrlen, paylen;
  InitHttpMessage(&msg, kHttpResponse);
  for (p = 0, hdrlen = paylen = t = i = n = 0;;) {
    if (i == n) {
      n += 1000;
      n += n >> 1;
      p = realloc(p, n);
    }
    if (usessl) {
      if ((rc = mbedtls_ssl_read(&ssl, p + i, n - i)) < 0) {
        if (rc == MBEDTLS_ERR_SSL_PEER_CLOSE_NOTIFY) {
          rc = 0;
        } else {
          tinyprint(2, prog,
                    ": ssl recv failed: ", DescribeMbedtlsErrorCode(rc), "\n",
                    NULL);
          exit(1);
        }
      }
    } else {
      if ((rc = read(sock, p + i, n - i)) == -1) {
        tinyprint(2, prog, ": recv failed: ", DescribeErrno(), "\n", NULL);
        exit(1);
      }
    }
    g = rc;
    i += g;
    switch (t) {
      case kHttpClientStateHeaders:
        unassert(g);
        if ((rc = ParseHttpMessage(&msg, p, i, n)) == -1) {
          tinyprint(2, prog, ": ", host, " sent bad http message\n", NULL);
          exit(1);
        }
        if (rc) {
          hdrlen = rc;
          if (100 <= msg.status && msg.status <= 199) {
            DestroyHttpMessage(&msg);
            InitHttpMessage(&msg, kHttpResponse);
            memmove(p, p + hdrlen, i - hdrlen);
            i -= hdrlen;
            break;
          }
          if (method == kHttpHead || includeheaders) {
            WriteOutput(p, hdrlen);
          }
          if (method == kHttpHead || msg.status == 204 || msg.status == 304) {
            goto Finished;
          }
          if (HasHeader(kHttpTransferEncoding) &&
              !HeaderEqualCase(kHttpTransferEncoding, "identity")) {
            if (!HeaderEqualCase(kHttpTransferEncoding, "chunked")) {
              tinyprint(2, prog, ": ", host,
                        " sent unsupported transfer encoding\n", NULL);
              exit(1);
            }
            t = kHttpClientStateBodyChunked;
            memset(&u, 0, sizeof(u));
            goto Chunked;
          } else if (HasHeader(kHttpContentLength)) {
            if ((rc = ParseContentLength(HeaderData(kHttpContentLength),
                                         HeaderLength(kHttpContentLength))) ==
                -1) {
              tinyprint(2, prog, ": ", host, " sent bad content length\n",
                        NULL);
              exit(1);
            }
            t = kHttpClientStateBodyLengthed;
            paylen = rc;
            if (paylen > i - hdrlen) {
              WriteOutput(p + hdrlen, i - hdrlen);
            } else {
              WriteOutput(p + hdrlen, paylen);
              goto Finished;
            }
          } else {
            t = kHttpClientStateBody;
            WriteOutput(p + hdrlen, i - hdrlen);
          }
        }
        break;
      case kHttpClientStateBody:
        WriteOutput(p + i - g, g);
        if (!g)
          goto Finished;
        break;
      case kHttpClientStateBodyLengthed:
        unassert(g);
        if (i - hdrlen > paylen) {
          g = hdrlen + paylen - (i - g);
        }
        WriteOutput(p + i - g, g);
        if (i - hdrlen >= paylen) {
          goto Finished;
        }
        break;
      case kHttpClientStateBodyChunked:
      Chunked:
        if ((rc = Unchunk(&u, p + hdrlen, i - hdrlen, &paylen)) == -1) {
          tinyprint(2, prog, ": ", host, " sent bad chunk coding\n", NULL);
          exit(1);
        }
        if (rc) {
          WriteOutput(p + hdrlen, paylen);
          goto Finished;
        }
        break;
      default:
        abort();
    }
  }

/*
 * Close connection.
 */
Finished:
  if (close(sock)) {
    tinyprint(2, prog, ": close failed: ", DescribeErrno(), "\n", NULL);
    exit(1);
  }

  /*
   * Free memory.
   */
  free(p);
  free(headers.p);
  if (usessl) {
    mbedtls_ssl_free(&ssl);
    mbedtls_ctr_drbg_free(&drbg);
    mbedtls_ssl_config_free(&conf);
    mbedtls_ctr_drbg_free(&drbg);
  }

  return 0;
}