/*

 * Copyright (c) 2015 DeNA Co., Ltd., Kazuho Oku

 *

 * Permission is hereby granted, free of charge, to any person obtaining a copy

 * of this software and associated documentation files (the "Software"), to

 * deal in the Software without restriction, including without limitation the

 * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or

 * sell copies of the Software, and to permit persons to whom the Software is

 * furnished to do so, subject to the following conditions:

 *

 * The above copyright notice and this permission notice shall be included in

 * all copies or substantial portions of the Software.

 *

 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR

 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,

 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE

 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER

 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING

 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS

 * IN THE SOFTWARE.

 */

#include "h2o.h"

struct st_headers_filter_t {

    h2o_filter_t super;

    h2o_headers_command_t *cmds;

};

struct st_headers_early_hints_handler_t {

    h2o_handler_t super;

    h2o_headers_command_t *cmds;

};

struct st_headers_early_hints_sender_t {

    h2o_req_t *req;

    h2o_headers_command_t *cmds;

    h2o_timer_t deferred_timeout_entry;

};

static void on_setup_ostream(h2o_filter_t *_self, h2o_req_t *req, h2o_ostream_t **slot)

{

    struct st_headers_filter_t *self = (void *)_self;

    h2o_headers_command_t *cmd;

    for (cmd = self->cmds; cmd->cmd != H2O_HEADERS_CMD_NULL; ++cmd) {

        if (cmd->when != H2O_HEADERS_CMD_WHEN_EARLY)

            h2o_rewrite_headers(&req->pool, &req->res.headers, cmd);

    }

    h2o_setup_next_ostream(req, slot);

}

static void on_informational(h2o_filter_t *_self, h2o_req_t *req)

{

    struct st_headers_filter_t *self = (void *)_self;

    h2o_headers_command_t *cmd;

    if (req->res.status != 103)

        return;

    for (cmd = self->cmds; cmd->cmd != H2O_HEADERS_CMD_NULL; ++cmd) {

        if (cmd->when != H2O_HEADERS_CMD_WHEN_FINAL)

            h2o_rewrite_headers(&req->pool, &req->res.headers, cmd);

    }

}

static void on_sender_deferred_timeout(h2o_timer_t *entry)

{

    struct st_headers_early_hints_sender_t *sender =

        H2O_STRUCT_FROM_MEMBER(struct st_headers_early_hints_sender_t, deferred_timeout_entry, entry);

    if (sender->req->res.status != 0)

        return;

    sender->req->res.status = 103;

    /* expect on_informational will be called and applies headers commands */

    h2o_send_informational(sender->req);

}

static void on_sender_dispose(void *_sender)

{

    struct st_headers_early_hints_sender_t *sender = (struct st_headers_early_hints_sender_t *)_sender;

    if (h2o_timer_is_linked(&sender->deferred_timeout_entry))

        h2o_timer_unlink(&sender->deferred_timeout_entry);

}

static int on_req(h2o_handler_t *_handler, h2o_req_t *req)

{

    struct st_headers_early_hints_handler_t *handler = (void *)_handler;

    struct st_headers_early_hints_sender_t *sender = h2o_mem_alloc_shared(&req->pool, sizeof(*sender), on_sender_dispose);

    sender->req = req;

    sender->cmds = handler->cmds;

    h2o_timer_init(&sender->deferred_timeout_entry, on_sender_deferred_timeout);

    h2o_timer_link(req->conn->ctx->loop, 0, &sender->deferred_timeout_entry);

    return -1;

}

static int requires_early_hints_handler(struct st_headers_filter_t *self)

{

    h2o_headers_command_t *cmd;

    for (cmd = self->cmds; cmd->cmd != H2O_HEADERS_CMD_NULL; ++cmd) {

        if (cmd->cmd != H2O_HEADERS_CMD_UNSET && cmd->when != H2O_HEADERS_CMD_WHEN_FINAL)

            return 1;

    }

    return 0;

}

void h2o_headers_register(h2o_pathconf_t *pathconf, h2o_headers_command_t *cmds)

{

    struct st_headers_filter_t *self = (void *)h2o_create_filter(pathconf, sizeof(*self));

    self->super.on_setup_ostream = on_setup_ostream;

    self->super.on_informational = on_informational;

    self->cmds = cmds;

    if (requires_early_hints_handler(self)) {

        struct st_headers_early_hints_handler_t *handler = (void *)h2o_create_handler(pathconf, sizeof(*handler));

        handler->cmds = cmds;

        handler->super.on_req = on_req;

        /* move this handler to first */

        memmove(pathconf->handlers.entries + 1, pathconf->handlers.entries,

                sizeof(h2o_handler_t *) * (pathconf->handlers.size - 1));

        pathconf->handlers.entries[0] = &handler->super;

    }

}

int h2o_headers_is_prohibited_name(const h2o_token_t *token)

{

    /* prohibit connection-specific headers */

    if (token == H2O_TOKEN_CONNECTION || token == H2O_TOKEN_CONTENT_LENGTH || token == H2O_TOKEN_TRANSFER_ENCODING)

        return 1;

    /* prohibit headers added at protocol layer */

    if (token == H2O_TOKEN_DATE || token == H2O_TOKEN_SERVER)

        return 1;

    /* all others are permitted */

    return 0;

}