#define MODULE "httpd"

#include "common.h"
#include "fw.h"
#include "httpd.h"

#include <incbin.h>
#include <unzipLIB.h>

/*
 * Allow the client to cache static content for this many seconds;
 * this improves responsiveness signficantly.
 */
#define HTTPD_STATIC_CACHE_AGE	300 /* 5 min */

static httpd_handle_t httpd;

#define TIMEBUF_LEN 32
static const char *http_date(const struct tm *when)
{
    static char timebuf[TIMEBUF_LEN];

    strftime(timebuf, TIMEBUF_LEN,
	     "%a, %d %b %Y %H:%M:%S GMT", when);

    return timebuf;
}

static const char *http_now(void)
{
    time_t t = time(NULL);
    return http_date(gmtime(&t));
}

static struct tm *set_weekday(struct tm *tm)
{
    /*
     * A variation on Zeller's congruence.
     */
    unsigned int c, y, m, d;

    y = tm->tm_year + 1900;
    m = tm->tm_mon + 2;
    d = tm->tm_mday;

    if (m < 4) {
	m += 12;
	y--;
    }

    c = y/100;

    tm->tm_wday = (d + ((13*m)/5) + y + (y >> 2) - c + (c >> 2) + 6) % 7;
    return tm;
}

static const char *http_dos_date(uint32_t dos_date)
{
    struct tm tm;

    tm.tm_sec   = (dos_date << 1) & 63;
    tm.tm_min   = (dos_date >> 5) & 63;
    tm.tm_hour  = (dos_date >> 11) & 31;
    tm.tm_mday  = (dos_date >> 16) & 31;
    tm.tm_mon   = ((dos_date >> 21) & 15) - 1;
    tm.tm_year  = (dos_date >> 25) + 80;
    tm.tm_isdst = 0;		/* Times are stored in GMT */

    return http_date(set_weekday(&tm));
}

static esp_err_t httpd_error(httpd_req_t *req,
			     unsigned int errcode, const char *msg)
{
    char *header = NULL;
    char *body = NULL;
    int hlen, blen;
    int rv = ESP_ERR_NO_MEM;

    blen = asprintf(&body, "%u %s\r\n", errcode, msg);

    if (!body)
	goto out;

    hlen = asprintf(&header,
		    "HTTP/1.1 %u %s\r\n"
		    "Content-Type: text/plain; charset=\"UTF-8\"\r\n"
		    "Content-Length: %d\r\n"
		    "Date: %s\r\n"
		    "Cache-Control: no-cache\r\n"
		    "Connection: close\r\n"
		    "\r\n",
		    errcode, msg, blen, http_now());

    if (!header)
	goto out;

    rv = httpd_send(req, header, hlen);
    if (!rv)
	rv = httpd_send(req, body, blen);

out:
    if (header)
	free(header);
    if (body)
	free(body);

    return rv;
}

esp_err_t httpd_firmware_upgrade_handler(httpd_req_t *req)
{
    char *response;
    esp_err_t err;
    int rv, len;

    printf("[POST] len = %zu uri = \"%s\"\n",
	   req->content_len, req->uri);

    if (!req->content_len) {
	return httpd_error(req, 411, "Length required");
    }

    rv = firmware_update((read_func_t)httpd_req_recv, (token_t)req);

    if (rv == FWUPDATE_ERR_IN_PROGRESS)
	return httpd_error(req, 409, "Firmware update already in progress");
    else if (rv)
	return httpd_error(req, 500, "Firmware update failed");

    len = asprintf(&response,
		   "Firmware update completed\r\n"
		   "Rebooting in %u seconds\r\n",
		   reboot_delayed());

    /* 200 is default, no need to set */
    httpd_resp_set_type(req, "text/plain; charset=\"UTF-8\"");
    httpd_resp_set_hdr(req, "Date", http_now());
    httpd_resp_set_hdr(req, "Cache-Control", "no-cache");
    httpd_resp_set_hdr(req, "Connection", "close");
    err = httpd_resp_send(req, response, len);
    free(response);

    return err;
}

INCBIN_EXTERN(wwwzip);

struct mime_type {
    const char *ext;
    uint16_t ext_len;
    uint16_t flags;
    const char *mime;
};

#define MT_CHARSET	1	/* Add charset to Content-Type */

static const struct mime_type mime_types[] = {
    { ".html",  5, MT_CHARSET, "text/html"                 },
    { ".xhtml", 6, MT_CHARSET, "text/html"                 },
    { ".css",   4, MT_CHARSET, "text/css"                  },
    { ".webp",  5, 0,          "image/webp"                },
    { ".jpg",   4, 0,          "image/jpeg"                },
    { ".png",   4, 0,          "image/png"                 },
    { ".ico",   4, 0,          "image/png"                 }, /* favicon.ico */
    { ".svg",   4, MT_CHARSET, "image/svg+xml"             },
    { ".otf",   4, 0,          "font/otf"                  },
    { ".ttf",   4, 0,          "font/ttf"                  },
    { ".woff",  5, 0,          "font/woff"                 },
    { ".woff2", 6, 0,          "font/woff2"                },
    { ".pdf",   4, 0,          "application/pdf"           },
    { ".js",    3, MT_CHARSET, "text/javascript"           },
    { ".mjs",   4, MT_CHARSET, "text/javascript"           },
    { ".json",  5, MT_CHARSET, "application/json"          },
    { ".xml",   4, MT_CHARSET, "text/xml"                  },
    { ".bin",   4, 0,          "application/octet-stream"  },
    { ".fw",    3, 0,          "application/octet-stream"  },
    { NULL,     0, MT_CHARSET, "text/plain"                }  /* default */
};

static esp_err_t httpd_static_handler(httpd_req_t *req)
{
    static const char index_filename[] = "index.html";
    const size_t buffer_size = UNZ_BUFSIZE;
    const char *uri, *enduri;
    bool add_index;
    char *buffer = NULL;
    ZIPFILE *zip = NULL;
    unzFile unz  = NULL;
    bool file_open = false;
    int err = 0;
    size_t len;

    uri = req->uri;
    while (*uri == '/')
	uri++;			/* Skip leading slashes */

    enduri = strchr(uri, '\0');
    if (enduri == uri) {
	add_index = true;
    } else if (enduri[-1] == '/') {
	add_index = true;
	enduri--;		/* Drop terminal slash */
    } else {
	add_index = false;	/* Try the plain filename first */
    }

    MSG("requesting: /%.*s\n", enduri - uri, uri);

    buffer = malloc(buffer_size);
    zip = malloc(sizeof *zip);
    if (!buffer || !zip) {
	err = httpd_error(req, 503, "Out of memory");
	goto out;
    }

    if (enduri - uri + 1 + sizeof index_filename >= buffer_size) {
	err = httpd_error(req, 414, "URI too long");
	goto out;
    }

    char *p = mempcpy(buffer, uri, enduri - uri);
    *p = '\0';

    unz = unzOpen(NULL, (void *)gwwwzipData, gwwwzipSize,
		  zip, NULL, NULL, NULL, NULL);
    if (!unz) {
	MSG("[HTTP] unzOpen failed!\n");
	err = httpd_error(req, 500, "Cannot open content archive");
	goto out;
    }

    while (1) {
	if (add_index) {
	    if (p > buffer)
		*p++ = '/';
	    memcpy(p, index_filename, sizeof index_filename);
	    p += sizeof index_filename - 1; /* Point to final NUL */
	}

	MSG("trying to open: %s\n", buffer);
	if (unzLocateFile(unz, buffer, 1) == UNZ_OK)
	    break;

	if (add_index) {
	    err = httpd_error(req, 404, "File not found");
	    goto out;
	}

	add_index = true;	/* Try again with the index filename */
    }

    /* Note: p points to the end of the filename string */
    size_t filelen = p - buffer;

    const struct mime_type *mime_type = mime_types;
    /* The default entry with length 0 will always match */
    while (mime_type->ext_len) {
	len = mime_type->ext_len;

	if (len < filelen && !memcmp(p - len, mime_type->ext, len))
	    break;

	mime_type++;
    }

    unz_file_info fileinfo;
    memset(&fileinfo, 0, sizeof fileinfo);
    unzGetCurrentFileInfo(unz, &fileinfo, NULL, 0, NULL, 0, NULL, 0);

    /*
     * Hopefully the combination of date and CRC
     * is strong enough to quality for a "strong" ETag
     */
    char etag[16+3+1];
    snprintf(etag, sizeof etag, "\"%08x:%08x\"",
	     fileinfo.dosDate, fileinfo.crc);

    bool skip_body = req->method == HTTP_HEAD || !fileinfo.uncompressed_size;
    bool skip_meta = false;
    const char *response = "200 OK";

    if (req->method == HTTP_GET &&
	httpd_req_get_hdr_value_str(req, "If-None-Match",
				    buffer, buffer_size) == ESP_OK &&
	strstr(buffer, etag)) {
	skip_body = skip_meta = true;
	response = "304 Not Modified";
    }

    len = snprintf(buffer, buffer_size-2,
		   "HTTP/1.1 %s\r\n"
		   "Date: %s\r\n"
		   "ETag: %s\r\n"
		   "Cache-Control: max-age=%d\r\n",
		   response,
		   http_now(),
		   etag,
		   HTTPD_STATIC_CACHE_AGE);

    if (len < buffer_size-2 && !skip_meta) {
	const char *mime_extra =
	    mime_type->flags & MT_CHARSET ? "; charset=\"UTF-8\"" : "";

	len += snprintf(buffer + len, buffer_size-2 - len,
			"Content-Type: %s%s\r\n"
			"Content-Length: %u\r\n"
			"Allow: GET, HEAD\r\n"
			"Last-Modified: %s\r\n"
			"%s",
			mime_type->mime, mime_extra,
			fileinfo.uncompressed_size,
			http_dos_date(fileinfo.dosDate),
			skip_body ? "" : "Connection: close\r\n");
    }

    if (len >= buffer_size-2) {
	err = httpd_resp_send_err(req, 500, "buffer_size too small");
	goto out;
    }

    buffer[len++] = '\r';
    buffer[len++] = '\n';

    err = httpd_send(req, buffer, len);
    if (skip_body || err != len) {
	/* No need to spend time uncompressing the file content */
	goto out;
    }

    if (unzOpenCurrentFile(unz) != UNZ_OK) {
	err = httpd_resp_send_err(req, 500, "Cannot open file in archive");
	goto out;
    }
    file_open = true;

    len = fileinfo.uncompressed_size;
    while (len) {
	size_t chunk = len;
	if (chunk > buffer_size)
	    chunk = buffer_size;

	if (unzReadCurrentFile(unz, buffer, chunk) != chunk) {
	    err = ESP_ERR_HTTPD_RESULT_TRUNC;
	    goto out;
	}

	err = httpd_send(req, buffer, chunk);
	if (err != chunk)
	    goto out;

	len -= chunk;
    }
    err = ESP_OK;		/* All good! */

out:
    if (file_open)
	unzCloseCurrentFile(unz);
    if (unz)
	unzClose(unz);
    if (zip)
	free(zip);
    if (buffer)
	free(buffer);

    return err;
}

static const httpd_uri_t uri_handlers[] = {
    {
	.uri      = "/*",
	.method   = HTTP_GET,
	.handler  = httpd_static_handler,
	.user_ctx = NULL
    },
    {
	.uri      = "/*",
	.method   = HTTP_HEAD,
	.handler  = httpd_static_handler,
	.user_ctx = NULL
    },
    {
	.uri      = "/fwupdate/?",
	.method   = HTTP_POST,
	.handler  = httpd_firmware_upgrade_handler,
	.user_ctx = NULL
    }
};

void my_httpd_stop(void)
{
    if (httpd) {
	httpd_stop(httpd);
	httpd = NULL;
    }
}

void my_httpd_start(void)
{
    httpd_config_t config = HTTPD_DEFAULT_CONFIG();
    httpd_handle_t server;

    if (httpd)
	return;

    config.task_priority = 2;

    printf("[HTTP] Default stack size: %zu\n", config.stack_size);
    config.stack_size <<= 2;
    printf("[HTTP] Requesting stack size: %zu\n", config.stack_size);

    config.uri_match_fn = httpd_uri_match_wildcard;

    if (httpd_start(&server, &config) != ESP_OK)
      return;

    httpd = server;
    for (size_t i = 0; i < ARRAY_SIZE(uri_handlers); i++)
	httpd_register_uri_handler(httpd, &uri_handlers[i]);

    printf("[HTTP] httpd started\n");
}