/*
Serval DNA - HTTP Server API
Copyright (C) 2013 Serval Project Inc.
 
This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 2
of the License, or (at your option) any later version.
 
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.
 
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
*/

#ifndef __SERVAL_DNA__HTTP_SERVER_H
#define __SERVAL_DNA__HTTP_SERVER_H

#include <stdint.h> // for uint16_t, uint8_t
#include <limits.h>
#include "lang.h" // for bool_t
#include "os.h" // for time_ms_t
#include "idebug.h" // for struct idebug
#include "strbuf.h"
#include "strbuf_helpers.h" // for struct json_atom
#include "fdqueue.h" // for struct sched_ent
#include "socket.h" // for struct socket_address

/* Generic HTTP request handling.
 *
 * @author Andrew Bettison <andrew@servalproject.com>
 */

extern const char HTTP_VERB_GET[];
extern const char HTTP_VERB_POST[];
extern const char HTTP_VERB_PUT[];
extern const char HTTP_VERB_HEAD[];
extern const char HTTP_VERB_DELETE[];
extern const char HTTP_VERB_TRACE[];
extern const char HTTP_VERB_OPTIONS[];
extern const char HTTP_VERB_CONNECT[];
extern const char HTTP_VERB_PATCH[];

typedef uint64_t http_size_t;
#define PRIhttp_size_t  PRIu64

struct http_request;

struct http_range {
  enum http_range_type { NIL = 0, CLOSED, OPEN, SUFFIX } type;
  http_size_t first; // only for CLOSED or OPEN
  http_size_t last; // only for CLOSED or SUFFIX
};

unsigned http_range_close(struct http_range *dst, const struct http_range *src, unsigned nranges, http_size_t content_length);
http_size_t http_range_bytes(const struct http_range *range, unsigned nranges);

#define CONTENT_LENGTH_UNKNOWN   UINT64_MAX

struct mime_content_type {
  char type[64];
  char subtype[64];
  char multipart_boundary[71];
  char charset[31];
  char format[31];
};

int mime_content_types_are_equal(const struct mime_content_type *a, const struct mime_content_type *b);

extern const struct mime_content_type CONTENT_TYPE_FAVICON;
extern const struct mime_content_type CONTENT_TYPE_TEXT;
extern const struct mime_content_type CONTENT_TYPE_HTML;
extern const struct mime_content_type CONTENT_TYPE_JSON;
extern const struct mime_content_type CONTENT_TYPE_BLOB;

struct http_client_authorization {
  enum http_authorization_scheme { NOAUTH = 0, BASIC } scheme;
  union {
    struct http_client_credentials_basic {
        const char *user;
        const char *password;
    } basic;
  } credentials;
};

struct http_www_authenticate {
  enum http_authorization_scheme scheme;
  const char *realm;
};

struct http_origin {
  uint8_t null;
  char scheme[10]; // enough for "https"
  char hostname[40]; // enough for "localhost"
  uint16_t port;
};

struct http_request_headers {
  http_size_t content_length;
  struct mime_content_type content_type;
  unsigned short content_range_count;
  struct http_origin origin;
  struct http_range content_ranges[5];
  struct http_client_authorization authorization;
  bool_t expect:1;
  bool_t chunked:1;
};

struct http_response_headers {
  uint8_t minor_version;
  http_size_t content_length;
  http_size_t content_range_start; // range_end = range_start + content_length - 1
  http_size_t resource_length; // size of entire resource
  const char *location; // used with 301 and 302 responses
  const struct mime_content_type *content_type; // one of the CONTENT_TYPE_ consts declared above
  const char *boundary;
  struct http_origin allow_origin;
  const char *allow_methods;
  const char *allow_headers;
  struct http_www_authenticate www_authenticate;
};

struct http_content_generator_result {
  size_t generated;
  size_t need;
};

typedef int (HTTP_CONTENT_GENERATOR)(struct http_request *, unsigned char *, size_t, struct http_content_generator_result *);

struct http_response {
  uint16_t status_code;
  const char *reason;
  struct {
    const char *label;
    struct json_atom value;
  } result_extra[4];
  struct http_response_headers header;
  const char *content;
  HTTP_CONTENT_GENERATOR *content_generator; // callback to produce more content
};

#define MIME_FILENAME_MAXLEN 127

struct mime_content_disposition {
  char type[64];
  char name[64];
  char filename[MIME_FILENAME_MAXLEN + 1];
  http_size_t size;
  time_t creation_date;
  time_t modification_date;
  time_t read_date;
};

struct mime_part_headers {
  http_size_t content_length;
  struct mime_content_type content_type;
  struct mime_content_disposition content_disposition;
};

struct http_mime_handler {
  // All these functions may abort the request processing by returning an HTTP
  // filure status code in the range 400-599 or by initiating an HTTP response
  // directly (changing the phase from RECEIVE to TRANSMIT).  They can return
  // zero to indicate that parsing should proceed.
  int (*handle_mime_preamble)(struct http_request *, char *, size_t);
  int (*handle_mime_part_start)(struct http_request *);
  int (*handle_mime_part_header)(struct http_request *, const struct mime_part_headers *);
  int (*handle_mime_body)(struct http_request *, char *, size_t);
  int (*handle_mime_part_end)(struct http_request *);
  int (*handle_mime_epilogue)(struct http_request *, char *, size_t);
};

struct http_request;

void http_request_init(struct http_request *r, int sockfd);
void http_request_free_response_buffer(struct http_request *r);
int http_request_set_response_bufsize(struct http_request *r, size_t bufsiz);
void http_request_finalise(struct http_request *r);
void http_request_pause_response(struct http_request *r, time_ms_t until);
void http_request_resume_response(struct http_request *r);
void http_request_response_static(struct http_request *r, int result, const struct mime_content_type *content_type, const char *body, uint64_t bytes);
void http_request_response_generated(struct http_request *r, int result, const struct mime_content_type *content_type, HTTP_CONTENT_GENERATOR *);
void http_request_simple_response(struct http_request *r, uint16_t result, const char *body);

typedef int (HTTP_CONTENT_GENERATOR_STRBUF_CHUNKER)(struct http_request *, strbuf);
int generate_http_content_from_strbuf_chunks(struct http_request *, char *, size_t, struct http_content_generator_result *, HTTP_CONTENT_GENERATOR_STRBUF_CHUNKER *);

typedef int HTTP_REQUEST_PARSER(struct http_request *);
typedef void HTTP_RENDERER(const struct http_request *, strbuf);

struct http_request {
  struct sched_ent alarm; // MUST BE FIRST ELEMENT
  // The following control the lifetime of this struct.
  enum http_request_phase { RECEIVE, TRANSMIT, PAUSE, DONE } phase;
  void (*finalise)(struct http_request *);
  void (*release)(void*);
  // Identify request from others being run.  Monotonic counter feeds it.  Only
  // used for debugging when we write post-<uuid>.log files for multi-part form
  // requests.
  unsigned int uuid;
  // These indirect debug flags allow different instances of HTTP servers to
  // control their debug output independently of each other.
  struct idebug debug;
  struct idebug disable_tx;
  // The following are used for parsing the HTTP request.
  time_ms_t initiate_time; // time connection was initiated
  time_ms_t idle_timeout; // disconnect if no bytes received for this long
  struct socket_address client_addr; // caller may supply this
  // The parsed HTTP request is accumulated into the following fields.
  const char *verb; // points to nul terminated static string, "GET", "PUT", etc.
  const char *path; // points into buffer; nul terminated
  struct query_parameter {
    const char *name; // points into buffer; nul terminated
    const char *value; // points into buffer; nul terminated
  }
    query_parameters[10]; // can make this as big as needed, but not dynamic
  uint8_t version_major; // m from from HTTP/m.n
  uint8_t version_minor; // n from HTTP/m.n
  struct http_request_headers request_header;
  // Parsing is done by setting 'parser' to point to a series of parsing
  // functions as the parsing state progresses.
  HTTP_REQUEST_PARSER *parser; // current parser function
  HTTP_REQUEST_PARSER *decoder; // decode any transfer encoding
  // The caller may set these up, and they are invoked by the parser as request
  // parsing reaches different stages.
  HTTP_REQUEST_PARSER *handle_first_line; // called after first line is parsed
  HTTP_REQUEST_PARSER *handle_headers; // called after all HTTP headers are parsed
  HTTP_REQUEST_PARSER *handle_content_end; // called after all content is received
  // The following are used for managing the buffer during RECEIVE phase.
  char *reserved; // end of reserved data in buffer[]
  char *received; // start of received data in buffer[]
  char *end_decoded; // end of decoded data in buffer[]
  char *decode_ptr; // end of received data in buffer[]
  char *end_received; // end of received data in buffer[]
  char *parsed; // start of unparsed data in buffer[]
  char *cursor; // for parsing
  http_size_t request_content_remaining;
  enum chunk_state {CHUNK_SIZE, CHUNK_DATA, CHUNK_NEWLINE} chunk_state;
  uint64_t chunk_size;
  // The following are used for parsing a multipart body.
  enum mime_state { START, PREAMBLE, HEADER, BODY, EPILOGUE } form_data_state;
  struct http_mime_handler form_data;
  struct mime_part_headers part_header;
  http_size_t part_body_length;
  // The following are used for constructing the response that will be sent in
  // TRANSMIT phase.
  struct http_response response;
  HTTP_RENDERER *render_extra_headers;
  // The following are used during TRANSMIT phase to control buffering and
  // sending.
  http_size_t response_length; // total response bytes (header + content)
  http_size_t response_sent; // for counting up to response_length
  char *response_buffer;
  size_t response_buffer_need;
  size_t response_buffer_size;
  size_t response_buffer_length;
  size_t response_buffer_sent;
  void (*response_free_buffer)(void*);
  // This buffer is used during RECEIVE and TRANSMIT phase.
  char buffer[8 * 1024];
};

/* Return the nul-terminated string value of a given query parameter: NULL if
 * no such parameter was supplied; HTTP_REQUEST_PARAM_NOVALUE if the parameter
 * was supplied without an '=value' part.
 */
const char *http_request_get_query_param(struct http_request *r, const char *name);
extern const char HTTP_REQUEST_PARAM_NOVALUE[];

#endif // __SERVAL_DNA__HTTP_SERVER_H