/*
 * Copyright (c) 2007, OmniTI Computer Consulting, Inc.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 * 
 *     * Redistributions of source code must retain the above copyright
 *       notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above
 *       copyright notice, this list of conditions and the following
 *       disclaimer in the documentation and/or other materials provided
 *       with the distribution.
 *     * Neither the name OmniTI Computer Consulting, Inc. nor the names
 *       of its contributors may be used to endorse or promote products
 *       derived from this software without specific prior written
 *       permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include "noit_defines.h"
#include "noit_listener.h"
#include "noit_http.h"
#include "noit_rest.h"
#include "noit_conf.h"

#include <pcre.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/mman.h>
#include <errno.h>

struct rest_xml_payload {
  char *buffer;
  xmlDocPtr indoc;
  int len;
  int allocd;
  int complete;
};

struct rest_url_dispatcher {
  char *method;
  pcre *expression;
  pcre_extra *extra;
  rest_request_handler handler;
  rest_authorize_func_t auth;
  /* Chain to the next one */
  struct rest_url_dispatcher *next;
};

struct rule_container {
  char *base;
  struct rest_url_dispatcher *rules;
  struct rest_url_dispatcher *rules_endptr;
};
noit_hash_table dispatch_points = NOIT_HASH_EMPTY;

struct noit_rest_acl_rule {
  noit_boolean allow;
  pcre *url;
  pcre *cn;
  struct noit_rest_acl_rule *next;
};
struct noit_rest_acl {
  noit_boolean allow;
  pcre *url;
  pcre *cn;
  struct noit_rest_acl_rule *rules;
  struct noit_rest_acl *next;
};

static struct noit_rest_acl *global_rest_acls = NULL;

static int
noit_http_rest_permission_denied(noit_http_rest_closure_t *restc,
                                 int npats, char **pats) {
  noit_http_session_ctx *ctx = restc->http_ctx;
  noit_http_response_standard(ctx, 403, "DENIED", "text/xml");
  noit_http_response_end(ctx);
  return 0;
}
static rest_request_handler
noit_http_get_handler(noit_http_rest_closure_t *restc) {
  struct rule_container *cont = NULL;
  struct rest_url_dispatcher *rule;
  noit_http_request *req = noit_http_session_request(restc->http_ctx);
  const char *uri_str;
  const char *eoq, *eob;
  uri_str = noit_http_request_uri_str(req);
  eoq = strchr(uri_str, '?');
  if(!eoq)
    eoq = uri_str + strlen(uri_str);
  eob = eoq - 1;

  /* find the right base */
  while(1) {
    void *vcont;
    while(eob >= uri_str && *eob != '/') eob--;
    if(eob < uri_str) break; /* off the front */
    if(noit_hash_retrieve(&dispatch_points, uri_str,
                          eob - uri_str + 1, &vcont)) {
      cont = vcont;
      eob++; /* move past the determined base */
      break;
    }
    eob--;
  }
  if(!cont) return NULL;
  for(rule = cont->rules; rule; rule = rule->next) {
    int ovector[30];
    int cnt;
    if(strcmp(rule->method, noit_http_request_method_str(req))) continue;
    if((cnt = pcre_exec(rule->expression, rule->extra, eob, eoq - eob, 0, 0,
                        ovector, sizeof(ovector)/sizeof(*ovector))) > 0) {
      /* We match, set 'er up */
      restc->fastpath = rule->handler;
      restc->nparams = cnt - 1;
      if(restc->nparams) {
        restc->params = calloc(restc->nparams, sizeof(*restc->params));
        for(cnt = 0; cnt < restc->nparams; cnt++) {
          int start = ovector[(cnt+1)*2];
          int end = ovector[(cnt+1)*2+1];
          restc->params[cnt] = malloc(end - start + 1);
          memcpy(restc->params[cnt], eob + start, end - start);
          restc->params[cnt][end - start] = '\0';
        }
      }
      if(rule->auth && !rule->auth(restc, restc->nparams, restc->params))
        return noit_http_rest_permission_denied;
      return restc->fastpath;
    }
  }
  return NULL;
}
noit_boolean
noit_http_rest_access(noit_http_rest_closure_t *restc,
                      int npats, char **pats) {
  struct noit_rest_acl *acl;
  struct noit_rest_acl_rule *rule;
  noit_http_request *req = noit_http_session_request(restc->http_ctx);
  const char *uri_str;
  int ovector[30];

  uri_str = noit_http_request_uri_str(req);
  for(acl = global_rest_acls; acl; acl = acl->next) {
    if(acl->cn && pcre_exec(acl->cn, NULL, "", 0, 0, 0,
                            ovector, sizeof(ovector)/sizeof(*ovector)) <= 0)
      continue;
    if(acl->url && pcre_exec(acl->url, NULL, uri_str, strlen(uri_str), 0, 0,
                             ovector, sizeof(ovector)/sizeof(*ovector)) <= 0)
      continue;
    for(rule = acl->rules; rule; rule = rule->next) {
      if(rule->cn && pcre_exec(rule->cn, NULL, "", 0, 0, 0,
                               ovector, sizeof(ovector)/sizeof(*ovector)) <= 0)
        continue;
      if(rule->url && pcre_exec(rule->url, NULL, uri_str, strlen(uri_str), 0, 0,
                                ovector, sizeof(ovector)/sizeof(*ovector)) <= 0)
        continue;
      return rule->allow;
    }
    return acl->allow;
  }
  return noit_false;
}
noit_boolean
noit_http_rest_client_cert_auth(noit_http_rest_closure_t *restc,
                                int npats, char **pats) {
  struct noit_rest_acl *acl;
  struct noit_rest_acl_rule *rule;
  noit_http_request *req = noit_http_session_request(restc->http_ctx);
  const char *uri_str;
  int ovector[30];

  uri_str = noit_http_request_uri_str(req);
  if(!restc->remote_cn || !strlen(restc->remote_cn)) return noit_false;
  for(acl = global_rest_acls; acl; acl = acl->next) {
    if(acl->cn && pcre_exec(acl->cn, NULL, restc->remote_cn,
                            strlen(restc->remote_cn), 0, 0,
                            ovector, sizeof(ovector)/sizeof(*ovector)) <= 0)
      continue;
    if(acl->url && pcre_exec(acl->url, NULL, uri_str, strlen(uri_str), 0, 0,
                             ovector, sizeof(ovector)/sizeof(*ovector)) <= 0)
      continue;
    for(rule = acl->rules; rule; rule = rule->next) {
      if(rule->cn && pcre_exec(rule->cn, NULL, restc->remote_cn,
                               strlen(restc->remote_cn), 0, 0,
                               ovector, sizeof(ovector)/sizeof(*ovector)) <= 0)
        continue;
      if(rule->url && pcre_exec(rule->url, NULL, uri_str, strlen(uri_str), 0, 0,
                                ovector, sizeof(ovector)/sizeof(*ovector)) <= 0)
        continue;
      return rule->allow;
    }
    return acl->allow;
  }
  return noit_false;
}
int
noit_http_rest_register(const char *method, const char *base,
                        const char *expr, rest_request_handler f) {
  return noit_http_rest_register_auth(method, base, expr, f, NULL);
}
int
noit_http_rest_register_auth(const char *method, const char *base,
                             const char *expr, rest_request_handler f,
                             rest_authorize_func_t auth) {
  void *vcont;
  struct rule_container *cont;
  struct rest_url_dispatcher *rule;
  const char *error;
  int erroffset;
  pcre *pcre_expr;
  int blen = strlen(base);
  /* base must end in a /, 'cause I said so */
  if(blen == 0 || base[blen-1] != '/') return -1;
  pcre_expr = pcre_compile(expr, 0, &error, &erroffset, NULL);
  if(!pcre_expr) {
    noitL(noit_error, "Error in rest expr(%s) '%s'@%d: %s\n",
          base, expr, erroffset, error);
    return -1;
  }
  rule = calloc(1, sizeof(*rule));
  rule->method = strdup(method);
  rule->expression = pcre_expr;
  rule->extra = pcre_study(rule->expression, 0, &error);
  rule->handler = f;
  rule->auth = auth;

  /* Make sure we have a container */
  if(!noit_hash_retrieve(&dispatch_points, base, strlen(base), &vcont)) {
    cont = calloc(1, sizeof(*cont));
    cont->base = strdup(base);
    noit_hash_store(&dispatch_points, cont->base, strlen(cont->base), cont);
  }
  else cont = vcont;

  /* Append the rule */
  if(cont->rules_endptr) {
    cont->rules_endptr->next = rule;
    cont->rules_endptr = cont->rules_endptr->next;
  }
  else
    cont->rules = cont->rules_endptr = rule;
  return 0;
}

static noit_http_rest_closure_t *
noit_http_rest_closure_alloc() {
  noit_http_rest_closure_t *restc;
  restc = calloc(1, sizeof(*restc));
  return restc;
}
static void
noit_http_rest_clean_request(noit_http_rest_closure_t *restc) {
  int i;
  if(restc->nparams) {
    for(i=0;i<restc->nparams;i++) free(restc->params[i]);
    free(restc->params);
  }
  if(restc->call_closure_free) restc->call_closure_free(restc->call_closure);
  restc->call_closure_free = NULL;
  restc->call_closure = NULL;
  restc->nparams = 0;
  restc->params = NULL;
  restc->fastpath = NULL;
}
void
noit_http_rest_closure_free(void *v) {
  noit_http_rest_closure_t *restc = v;
  free(restc->remote_cn);
  noit_http_rest_clean_request(restc);
  free(restc);
}

int
noit_rest_request_dispatcher(noit_http_session_ctx *ctx) {
  noit_http_rest_closure_t *restc = noit_http_session_dispatcher_closure(ctx);
  rest_request_handler handler = restc->fastpath;
  if(!handler) handler = noit_http_get_handler(restc);
  if(handler) {
    void *old_closure = restc, *new_closure;
    noit_http_response *res = noit_http_session_response(ctx);
    int rv;
    rv = handler(restc, restc->nparams, restc->params);
    /* If the request is closed, we need to cleanup.  However
     * if the dispatch closure has changed, the callee has done
     * something (presumably freeing the restc in the process)
     * and it would be unsafe for us to free it as well.
     */
    new_closure = noit_http_session_dispatcher_closure(ctx);
    if(old_closure == new_closure &&
       noit_http_response_closed(res)) noit_http_rest_clean_request(restc);
    return rv;
  }
  noit_http_response_status_set(ctx, 404, "NOT FOUND");
  noit_http_response_option_set(ctx, NOIT_HTTP_CHUNKED);
  noit_http_rest_clean_request(restc);
  noit_http_response_end(ctx);
  return 0;
}

int
noit_http_rest_handler(eventer_t e, int mask, void *closure,
                       struct timeval *now) {
  int newmask = EVENTER_READ | EVENTER_EXCEPTION, rv, done = 0;
  acceptor_closure_t *ac = closure;
  noit_http_rest_closure_t *restc = ac->service_ctx;

  if(mask & EVENTER_EXCEPTION || (restc && restc->wants_shutdown)) {
socket_error:
    /* Exceptions cause us to simply snip the connection */
    eventer_remove_fd(e->fd);
    e->opset->close(e->fd, &newmask, e);
    if(ac) acceptor_closure_free(ac);
    return 0;
  }

  if(!ac->service_ctx) {
    const char *primer = "";
    ac->service_ctx = restc = noit_http_rest_closure_alloc();
    ac->service_ctx_free = noit_http_rest_closure_free;
    restc->ac = ac;
    restc->remote_cn = strdup(ac->remote_cn ? ac->remote_cn : "");
    restc->http_ctx =
        noit_http_session_ctx_new(noit_rest_request_dispatcher,
                                  restc, e, ac);
    
    switch(ac->cmd) {
      case NOIT_CONTROL_DELETE:
        primer = "DELE";
        break;
      case NOIT_CONTROL_GET:
        primer = "GET ";
        break;
      case NOIT_CONTROL_HEAD:
        primer = "HEAD";
        break;
      case NOIT_CONTROL_POST:
        primer = "POST";
        break;
      case NOIT_CONTROL_PUT:
        primer = "PUT ";
        break;
      case NOIT_CONTROL_MERGE:
        primer = "MERG";
        break;
      default:
        goto socket_error;
    }
    noit_http_session_prime_input(restc->http_ctx, primer, 4);
  }
  rv = noit_http_session_drive(e, mask, restc->http_ctx, now, &done);
  if(done) {
    if(ac) acceptor_closure_free(ac);
  }
  return rv;
}

int
noit_http_rest_raw_handler(eventer_t e, int mask, void *closure,
                           struct timeval *now) {
  int newmask = EVENTER_READ | EVENTER_EXCEPTION, rv, done = 0;
  acceptor_closure_t *ac = closure;
  noit_http_rest_closure_t *restc = ac->service_ctx;

  if(mask & EVENTER_EXCEPTION || (restc && restc->wants_shutdown)) {
    /* Exceptions cause us to simply snip the connection */
    eventer_remove_fd(e->fd);
    e->opset->close(e->fd, &newmask, e);
    if(ac) acceptor_closure_free(ac);
    return 0;
  }
  if(!ac->service_ctx) {
    ac->service_ctx = restc = noit_http_rest_closure_alloc();
    ac->service_ctx_free = noit_http_rest_closure_free;
    restc->ac = ac;
    restc->http_ctx =
        noit_http_session_ctx_new(noit_rest_request_dispatcher,
                                  restc, e, ac);
  }
  rv = noit_http_session_drive(e, mask, restc->http_ctx, now, &done);
  if(done) {
    if(ac) acceptor_closure_free(ac);
  }
  return rv;
}

static void
rest_xml_payload_free(void *f) {
  struct rest_xml_payload *xmlin = f;
  if(xmlin->buffer) free(xmlin->buffer);
  if(xmlin->indoc) xmlFreeDoc(xmlin->indoc);
}

xmlDocPtr
rest_get_xml_upload(noit_http_rest_closure_t *restc,
                    int *mask, int *complete) {
  struct rest_xml_payload *rxc;
  noit_http_request *req = noit_http_session_request(restc->http_ctx);

  if(restc->call_closure == NULL) {
    restc->call_closure = calloc(1, sizeof(*rxc));
    restc->call_closure_free = rest_xml_payload_free;
  }
  rxc = restc->call_closure;
  while(!rxc->complete) {
    int len;
    if(rxc->len == rxc->allocd) {
      char *b;
      rxc->allocd += 32768;
      b = rxc->buffer ? realloc(rxc->buffer, rxc->allocd) :
                        malloc(rxc->allocd);
      if(!b) {
        *complete = 1;
        return NULL;
      }
      rxc->buffer = b;
    }
    len = noit_http_session_req_consume(restc->http_ctx,
                                        rxc->buffer + rxc->len,
                                        rxc->allocd - rxc->len,
                                        mask);
    if(len > 0) rxc->len += len;
    if(len < 0 && errno == EAGAIN) return NULL;
    else if(len < 0) {
      *complete = 1;
      return NULL;
    }
    if(rxc->len == noit_http_request_content_length(req)) {
      rxc->indoc = xmlParseMemory(rxc->buffer, rxc->len);
      rxc->complete = 1;
    }
  }

  *complete = 1;
  return rxc->indoc;
}
int
noit_rest_simple_file_handler(noit_http_rest_closure_t *restc,
                              int npats, char **pats) {
  int drlen = 0;
  const char *document_root = NULL;
  const char *index_file = NULL;
  noit_http_session_ctx *ctx = restc->http_ctx;
  char file[PATH_MAX], rfile[PATH_MAX];
  struct stat st;
  int fd;
  void *contents = MAP_FAILED;

  if(npats != 1 ||
     !noit_hash_retr_str(restc->ac->config,
                         "document_root", strlen("document_root"),
                         &document_root)) {
    goto not_found;
  }
  if(!noit_hash_retr_str(restc->ac->config,
                         "index_file", strlen("index_file"),
                         &index_file)) {
    index_file = "index.html";
  }
  drlen = strlen(document_root);
  snprintf(file, sizeof(file), "%s/%s", document_root, pats[0]);
  if(file[strlen(file) - 1] == '/') {
    snprintf(file + strlen(file), sizeof(file) - strlen(file),
             "%s", index_file);
  }
  /* resolve */
  if(realpath(file, rfile) == NULL) goto not_found;
  /* restrict */
  if(strncmp(rfile, document_root, drlen)) goto denied;
  if(rfile[drlen] != '/' && rfile[drlen + 1] != '/') goto denied;
  /* stat */
  if(stat(rfile, &st) != 0) {
    switch (errno) {
      case EACCES: goto denied;
      default: goto not_found;
    }
  }
  /* open */
  if(st.st_size > 0) {
    fd = open(rfile, O_RDONLY);
    if(fd < 0) goto not_found;
    contents = mmap(NULL, st.st_size, PROT_READ, MAP_SHARED, fd, 0);
    close(fd);
    if(contents == MAP_FAILED) goto not_found;
  }
  noit_http_response_ok(ctx, "text/html");
  if(st.st_size > 0) {
    noit_http_response_append(ctx, contents, st.st_size);
    munmap(contents, st.st_size);
  }
  noit_http_response_end(ctx);
  return 0;

 denied:
  noit_http_response_denied(ctx, "text/html");
  noit_http_response_end(ctx);
  return 0;
 not_found:
  noit_http_response_not_found(ctx, "text/html");
  noit_http_response_end(ctx);
  return 0;
}

void noit_http_rest_load_rules() {
  int ai, cnt = 0;
  noit_conf_section_t *acls;
  char path[256];
  struct noit_rest_acl *newhead = NULL, *oldacls, *remove_acl;
  struct noit_rest_acl_rule *remove_rule;

  snprintf(path, sizeof(path), "//rest//acl");
  acls = noit_conf_get_sections(NULL, path, &cnt);
  noitL(noit_stderr, "Found %d acl stanzas\n", cnt);
  for(ai = cnt-1; ai>=0; ai--) {
    char tbuff[32];
    struct noit_rest_acl *newacl;
    int ri, rcnt = 0;
    noit_boolean default_allow = noit_false;
    noit_conf_section_t *rules;

    newacl = calloc(1, sizeof(*newacl));
    newacl->next = newhead;
    newhead = newacl;
    if(noit_conf_get_stringbuf(acls[ai], "@type", tbuff, sizeof(tbuff)) &&
       !strcmp(tbuff, "allow"))
      newacl->allow = noit_true;

#define compile_re(node, cont, name) do { \
  char buff[256]; \
  if(noit_conf_get_stringbuf(node, "@" #name, buff, sizeof(buff))) { \
    const char *error; \
    int erroffset; \
    cont->name = pcre_compile(buff, 0, &error, &erroffset, NULL); \
  } \
} while(0)

    newacl->allow = default_allow;
    compile_re(acls[ai], newacl, cn);
    compile_re(acls[ai], newacl, url);
    rules = noit_conf_get_sections(acls[ai], "rule", &rcnt);
    for(ri = rcnt - 1; ri >= 0; ri--) {
      struct noit_rest_acl_rule *newacl_rule;
      newacl_rule = calloc(1, sizeof(*newacl_rule));
      newacl_rule->next = newacl->rules;
      newacl->rules = newacl_rule;
      if(noit_conf_get_stringbuf(rules[ri], "@type", tbuff, sizeof(tbuff)) &&
         !strcmp(tbuff, "allow"))
        newacl_rule->allow = noit_true;
      compile_re(rules[ri], newacl_rule, cn);
      compile_re(rules[ri], newacl_rule, url);
    }
    free(rules);
  }
  free(acls);

  oldacls = global_rest_acls;
  global_rest_acls = newhead;

  while(oldacls) {
    remove_acl = oldacls->next;
    while(oldacls->rules) {
      remove_rule = oldacls->rules->next;
      if(oldacls->rules->cn) pcre_free(oldacls->rules->cn);
      if(oldacls->rules->url) pcre_free(oldacls->rules->url);
      free(oldacls->rules);
      oldacls->rules = remove_rule;
    }
    if(oldacls->cn) pcre_free(oldacls->cn);
    if(oldacls->url) pcre_free(oldacls->url);
    free(oldacls);
    oldacls = remove_acl;
  }
}
void noit_http_rest_init() {
  noit_http_init();
  eventer_name_callback("noit_wire_rest_api/1.0", noit_http_rest_handler);
  eventer_name_callback("http_rest_api", noit_http_rest_raw_handler);

  noit_http_rest_load_rules();

  noit_control_dispatch_delegate(noit_control_dispatch,
                                 NOIT_CONTROL_DELETE,
                                 noit_http_rest_handler);
  noit_control_dispatch_delegate(noit_control_dispatch,
                                 NOIT_CONTROL_MERGE,
                                 noit_http_rest_handler);
  noit_control_dispatch_delegate(noit_control_dispatch,
                                 NOIT_CONTROL_GET,
                                 noit_http_rest_handler);
  noit_control_dispatch_delegate(noit_control_dispatch,
                                 NOIT_CONTROL_HEAD,
                                 noit_http_rest_handler);
  noit_control_dispatch_delegate(noit_control_dispatch,
                                 NOIT_CONTROL_POST,
                                 noit_http_rest_handler);
  noit_control_dispatch_delegate(noit_control_dispatch,
                                 NOIT_CONTROL_PUT,
                                 noit_http_rest_handler);
}