#include "first.h"

#include "base.h"
#include "array.h"
#include "buffer.h"
#include "log.h"
#include "http_header.h"

#include "plugin.h"
#include "stat_cache.h"

#include <stdlib.h>
#include <string.h>
#include <time.h>

/**
 * set HTTP headers Cache-Control and Expires
 */

typedef struct {
    const array *expire_url;
    const array *expire_mimetypes;
} plugin_config;

typedef struct {
    PLUGIN_DATA;
    plugin_config defaults;
    plugin_config conf;
} plugin_data;

INIT_FUNC(mod_expire_init) {
    return calloc(1, sizeof(plugin_data));
}

static int mod_expire_get_offset(log_error_st *errh, const buffer *expire, time_t *offset) {
	char *ts;
	int type = -1;
	time_t retts = 0;

	/*
	 * parse
	 *
	 * '(access|now|modification) [plus] {<num> <type>}*'
	 *
	 * e.g. 'access 1 years'
	 */

	if (buffer_string_is_empty(expire)) {
		log_error(errh, __FILE__, __LINE__, "mod_expire empty string");
		return -1;
	}

	ts = expire->ptr;

	if (0 == strncmp(ts, "access ", 7)) {
		type  = 0;
		ts   += 7;
	} else if (0 == strncmp(ts, "now ", 4)) {
		type  = 0;
		ts   += 4;
	} else if (0 == strncmp(ts, "modification ", 13)) {
		type  = 1;
		ts   += 13;
	} else {
		/* invalid type-prefix */
		log_error(errh, __FILE__, __LINE__, "invalid <base>: %s", ts);
		return -1;
	}

	if (0 == strncmp(ts, "plus ", 5)) {
		/* skip the optional plus */
		ts   += 5;
	}

	/* the rest is just <number> (years|months|weeks|days|hours|minutes|seconds) */
	while (1) {
		char *space, *err;
		int num;

		if (NULL == (space = strchr(ts, ' '))) {
			log_error(errh, __FILE__, __LINE__,
			  "missing space after <num>: %s", ts);
			return -1;
		}

		num = strtol(ts, &err, 10);
		if (*err != ' ') {
			log_error(errh, __FILE__, __LINE__,
			  "missing <type> after <num>: %s", ts);
			return -1;
		}

		ts = space + 1;

		if (NULL != (space = strchr(ts, ' '))) {
			int slen;
			/* */

			slen = space - ts;

			if (slen == 5 &&
			    0 == strncmp(ts, "years", slen)) {
				num *= 60 * 60 * 24 * 30 * 12;
			} else if (slen == 6 &&
				   0 == strncmp(ts, "months", slen)) {
				num *= 60 * 60 * 24 * 30;
			} else if (slen == 5 &&
				   0 == strncmp(ts, "weeks", slen)) {
				num *= 60 * 60 * 24 * 7;
			} else if (slen == 4 &&
				   0 == strncmp(ts, "days", slen)) {
				num *= 60 * 60 * 24;
			} else if (slen == 5 &&
				   0 == strncmp(ts, "hours", slen)) {
				num *= 60 * 60;
			} else if (slen == 7 &&
				   0 == strncmp(ts, "minutes", slen)) {
				num *= 60;
			} else if (slen == 7 &&
				   0 == strncmp(ts, "seconds", slen)) {
				num *= 1;
			} else {
				log_error(errh, __FILE__, __LINE__, "unknown type: %s", ts);
				return -1;
			}

			retts += num;

			ts = space + 1;
		} else {
			if (0 == strcmp(ts, "years")) {
				num *= 60 * 60 * 24 * 30 * 12;
			} else if (0 == strcmp(ts, "months")) {
				num *= 60 * 60 * 24 * 30;
			} else if (0 == strcmp(ts, "weeks")) {
				num *= 60 * 60 * 24 * 7;
			} else if (0 == strcmp(ts, "days")) {
				num *= 60 * 60 * 24;
			} else if (0 == strcmp(ts, "hours")) {
				num *= 60 * 60;
			} else if (0 == strcmp(ts, "minutes")) {
				num *= 60;
			} else if (0 == strcmp(ts, "seconds")) {
				num *= 1;
			} else {
				log_error(errh, __FILE__, __LINE__, "unknown type: %s", ts);
				return -1;
			}

			retts += num;

			break;
		}
	}

	if (offset != NULL) *offset = retts;

	return type;
}

static void mod_expire_merge_config_cpv(plugin_config * const pconf, const config_plugin_value_t * const cpv) {
    switch (cpv->k_id) { /* index into static config_plugin_keys_t cpk[] */
      case 0: /* expire.url */
        pconf->expire_url = cpv->v.a;
        break;
      case 1: /* expire.mimetypes */
        pconf->expire_mimetypes = cpv->v.a;
        break;
      default:/* should not happen */
        return;
    }
}

static void mod_expire_merge_config(plugin_config * const pconf, const config_plugin_value_t *cpv) {
    do {
        mod_expire_merge_config_cpv(pconf, cpv);
    } while ((++cpv)->k_id != -1);
}

static void mod_expire_patch_config(connection * const con, plugin_data * const p) {
    memcpy(&p->conf, &p->defaults, sizeof(plugin_config));
    for (int i = 1, used = p->nconfig; i < used; ++i) {
        if (config_check_cond(con, (uint32_t)p->cvlist[i].k_id))
            mod_expire_merge_config(&p->conf, p->cvlist + p->cvlist[i].v.u2[0]);
    }
}

SETDEFAULTS_FUNC(mod_expire_set_defaults) {
    static const config_plugin_keys_t cpk[] = {
      { CONST_STR_LEN("expire.url"),
        T_CONFIG_ARRAY,
        T_CONFIG_SCOPE_CONNECTION }
     ,{ CONST_STR_LEN("expire.mimetypes"),
        T_CONFIG_ARRAY,
        T_CONFIG_SCOPE_CONNECTION }
     ,{ NULL, 0,
        T_CONFIG_UNSET,
        T_CONFIG_SCOPE_UNSET }
    };

    plugin_data * const p = p_d;
    if (!config_plugin_values_init(srv, p, cpk, "mod_expire"))
        return HANDLER_ERROR;

    /* process and validate config directives
     * (init i to 0 if global context; to 1 to skip empty global context) */
    for (int i = !p->cvlist[0].v.u2[1]; i < p->nconfig; ++i) {
        const config_plugin_value_t *cpv = p->cvlist + p->cvlist[i].v.u2[0];
        for (; -1 != cpv->k_id; ++cpv) {
            switch (cpv->k_id) {
              case 0: /* expire.url */
                if (!array_is_kvstring(cpv->v.a)) {
                    log_error(srv->errh, __FILE__, __LINE__,
                      "unexpected value for %s; "
                      "expected list of \"urlpath\" => \"expiration\"",
                      cpk[cpv->k_id].k);
                    return HANDLER_ERROR;
                }
                for (uint32_t k = 0; k < cpv->v.a->used; ++k) {
                    /* parse lines */
                    data_string *ds = (data_string *)cpv->v.a->data[k];
                    if (-1 == mod_expire_get_offset(srv->errh,&ds->value,NULL)){
                        log_error(srv->errh, __FILE__, __LINE__,
                          "parsing expire.url failed: %s", ds->value.ptr);
                        return HANDLER_ERROR;
                    }
                }
                break;
              case 1: /* expire.mimetypes */
                if (!array_is_kvstring(cpv->v.a)) {
                    log_error(srv->errh, __FILE__, __LINE__,
                      "unexpected value for %s; "
                      "expected list of \"mimetype\" => \"expiration\"",
                      cpk[cpv->k_id].k);
                    return HANDLER_ERROR;
                }
                for (uint32_t k = 0; k < cpv->v.a->used; ++k) {
                    data_string *ds = (data_string *)cpv->v.a->data[k];

                    /*(omit trailing '*', if present, from prefix match)*/
                    /*(not usually a good idea to modify array keys
                     * since doing so might break array_get_element_klen()
                     * search, but array use in this module only walks array)*/
                    size_t klen = buffer_string_length(&ds->key);
                    if (klen && ds->key.ptr[klen-1] == '*')
                        buffer_string_set_length(&ds->key, klen-1);

                    /* parse lines */
                    if (-1 == mod_expire_get_offset(srv->errh,&ds->value,NULL)){
                        log_error(srv->errh, __FILE__, __LINE__,
                          "parsing expire.mimetypes failed: %s", ds->value.ptr);
                        return HANDLER_ERROR;
                    }
                }
                break;
              default:/* should not happen */
                break;
            }
        }
    }

    /* initialize p->defaults from global config context */
    if (p->nconfig > 0 && p->cvlist->v.u2[1]) {
        const config_plugin_value_t *cpv = p->cvlist + p->cvlist->v.u2[0];
        if (-1 != cpv->k_id)
            mod_expire_merge_config(&p->defaults, cpv);
    }

    return HANDLER_GO_ON;
}

CONNECTION_FUNC(mod_expire_handler) {
	plugin_data *p = p_d;
	const buffer *vb;
	const data_string *ds;

	/* Add caching headers only to http_status 200 OK or 206 Partial Content */
	if (con->http_status != 200 && con->http_status != 206) return HANDLER_GO_ON;
	/* Add caching headers only to GET or HEAD requests */
	if (   con->request.http_method != HTTP_METHOD_GET
	    && con->request.http_method != HTTP_METHOD_HEAD) return HANDLER_GO_ON;
	/* Add caching headers only if not already present */
	vb = http_header_response_get(con, HTTP_HEADER_CACHE_CONTROL, CONST_STR_LEN("Cache-Control"));
	if (NULL != vb) return HANDLER_GO_ON;

	if (buffer_is_empty(con->uri.path)) return HANDLER_GO_ON;

	mod_expire_patch_config(con, p);

	/* check expire.url */
	ds = p->conf.expire_url
	  ? (const data_string *)array_match_key_prefix(p->conf.expire_url, con->uri.path)
	  : NULL;
	if (NULL != ds) {
		vb = &ds->value;
	}
	else {
		/* check expire.mimetypes (if no match with expire.url) */
		if (NULL == p->conf.expire_mimetypes) return HANDLER_GO_ON;
		vb = http_header_response_get(con, HTTP_HEADER_CONTENT_TYPE, CONST_STR_LEN("Content-Type"));
		ds = (NULL != vb)
		   ? (const data_string *)array_match_key_prefix(p->conf.expire_mimetypes, vb)
		   : (const data_string *)array_get_element_klen(p->conf.expire_mimetypes, CONST_STR_LEN(""));
		if (NULL == ds) return HANDLER_GO_ON;
		vb = &ds->value;
	}

	if (NULL != vb) {
			time_t ts, expires;
			const time_t cur_ts = log_epoch_secs;
			stat_cache_entry *sce = NULL;

			switch(mod_expire_get_offset(con->conf.errh, vb, &ts)) {
			case 0:
				/* access */
				expires = (ts + cur_ts);
				break;
			case 1:
				/* modification */

				sce = stat_cache_get_entry(con->physical.path);

				/* can't set modification based expire header if
				 * mtime is not available
				 */
				if (NULL == sce) return HANDLER_GO_ON;

				expires = (ts + sce->st.st_mtime);
				break;
			default:
				/* -1 is handled at parse-time */
				return HANDLER_ERROR;
			}

			/* expires should be at least cur_ts */
			if (expires < cur_ts) expires = cur_ts;

			buffer * const tb = con->srv->tmp_buf;

			/* HTTP/1.0 */
			buffer_clear(tb);
			buffer_append_strftime(tb, "%a, %d %b %Y %H:%M:%S GMT", gmtime(&(expires)));
			http_header_response_set(con, HTTP_HEADER_OTHER, CONST_STR_LEN("Expires"), CONST_BUF_LEN(tb));

			/* HTTP/1.1 */
			buffer_copy_string_len(tb, CONST_STR_LEN("max-age="));
			buffer_append_int(tb, expires - cur_ts); /* as expires >= cur_ts the difference is >= 0 */

			http_header_response_set(con, HTTP_HEADER_CACHE_CONTROL, CONST_STR_LEN("Cache-Control"), CONST_BUF_LEN(tb));

			return HANDLER_GO_ON;
	}

	/* not found */
	return HANDLER_GO_ON;
}


int mod_expire_plugin_init(plugin *p);
int mod_expire_plugin_init(plugin *p) {
	p->version     = LIGHTTPD_VERSION_ID;
	p->name        = "expire";

	p->init        = mod_expire_init;
	p->handle_response_start = mod_expire_handler;
	p->set_defaults  = mod_expire_set_defaults;

	return 0;
}