/**
 * @file main.c
 * @brief Main entry point for the cinst process.
 *
 *  The cinst process may or may not be run with elevated
 *  privileges. When run with elevated privileges this
 *  process will modify system wide certificate stores.
 *  Otherwise only the users certificate stores are modified.
 *
 *  It expects a certificatelist on stdin enclosed in a
 *  -----BEGIN CERTIFICATE LIST-----
 *  ...
 *  -----END CERTIFICATE LIST-----
 *
 *  Followed by additional instruction lines of:
 *  I:<certificate>
 *  R:<certificate>
 *
 *  It will only execute the instructions if the
 *  I and R instructions are also part of the signed
 *  certificate list. The signature is validated with the
 *  built in key.
 *
 *  The special instruction "UNINSTALL" will cause the installer
 *  to remove all certificates (Even those marked with I) that
 *  are part of the list to be removed.
 *
 **/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <assert.h>
#include <stdbool.h>

#include "strhelp.h"
#include "listutil.h"
#include "errorcodes.h"
#include "windowsstore.h"

/* The certificate list + instructions may only be so long as
 * twice the accepted certificatelist size */
#define MAX_INPUT_SIZE MAX_LINE_LENGTH * MAX_LINES * 2

/* @brief Read stdin into data structures.
 *
 * Reads from stdin and sorts the input into the respective
 * variables. The pointers returned need to be freed by the caller.
 * Terminates in OOM conditions.
 *
 * The caller needs to free the memory allocated by this function
 * even when an error is returned.
 *
 * Uninstall certificates are all certificates that are pa
 *
 * @param[out] certificate_list the parsed certificate list
 * @param[out] to_install strv of installation instructions or NULL
 * @param[out] to_remove strv of remove instructions or NULL
 * @param[out] all_certs strv of uninstallation instructions or NULL
 *
 * @returns: 0 on success. An error code otherwise.
 */
int readInput(char **certificate_list, char ***to_install,
              char ***to_remove, char ***all_certs)
{
    int lines_read = 0;
    int readingList = 0;
    size_t list_size = 0;
    char buf[MAX_LINE_LENGTH + 2];

    if (*certificate_list || *to_install || *to_remove) {
        printf("Error invalid parameters\n");
        return -1;
    }

    while (fgets(buf, MAX_LINE_LENGTH + 1, stdin)) {
        size_t len = strlen(buf); /* fgets ensures buf is terminated */
        if (len <= 3) {
            printf("Line too short.\n");
            return ERR_INVALID_INPUT;
        }
        if (lines_read ++ > MAX_LINES) {
            printf("Too many lines\n");
            return ERR_TOO_MUCH_INPUT;
        }

        if (buf[len-2] != '\r') {
            if (buf[len-1] != '\n') {
                printf("Line too long.\n");
                return ERR_INVALID_INPUT;
            }
            buf[len-1] = '\r';
            buf[len] = '\n';
            buf[len+1] = '\0';
            len++;
        }

        if (strcmp("-----BEGIN CERTIFICATE LIST-----\r\n", buf) == 0){
            readingList = 1;
            continue;
        }
        if (strcmp("-----END CERTIFICATE LIST-----\r\n", buf) == 0){
            readingList = 0;
            continue;
        }
        if (readingList) {
            str_append_str(certificate_list, &list_size, buf, len);
        } else if (strcmp("UNINSTALL\r\n", buf) == 0) {
            /* Remove trailing \r\n */
            strv_append(to_remove, buf, len - 2);
            continue;
        }
        if (*buf == 'I') {
            /* Remove leading I: and trailing \r\n */
            strv_append(readingList ? all_certs : to_install,
                    buf+2, len - 4);
            continue;
        }
        if (*buf == 'R') {
            /* Remove leading R: and trailing \r\n */
            strv_append(readingList ? all_certs : to_remove,
                    buf+2, len - 4);
            continue;
        }
    }

    return 0;
}

/** @brief Check that the insturctions match to the list
 *
 * Only certificates part of the certificate_list are allowed
 * for installation.
 *
 * @param[in] all_certs strv of all valid certificates in a list
 * @param[in] to_validate strv of instructions
 *
 * @returns 0 on success, an error otherwise
 */
int validate_instructions(char **all_certs,
                          char **to_validate)
{
    int i = 0,
        j = 0;

    if (!all_certs || strv_length(all_certs) < 1) {
        /* Invalid parameters */
        return -1;
    }

    if (to_validate == NULL) {
        /* Nothing is valid */
        return 0;
    }

    for (i=0; to_validate[i]; i++) {
        bool found = false;
        for (j=0; all_certs[j]; j++) {
            if (strncmp(to_validate[i], all_certs[j], MAX_LINE_LENGTH - 2) == 0) {
                found = true;
                break;
            }
        }
        if (!found) {
            printf("Install instruction with invalid certificate\n.");
            return ERR_INVALID_INSTRUCTIONS;
        }
    }

    return 0;
}


int main() {
    char **to_install = NULL;
    char **to_remove = NULL;
    char **all_certs = NULL;
    char *certificate_list = NULL;
    size_t list_len = 0;
    int ret = -1;
    bool uninstall = false;

    ret = readInput(&certificate_list, &to_install, &to_remove, &all_certs);

    if (ret) {
        return ret;
    }

    if (!certificate_list) {
        return ERR_INVALID_INPUT_NO_LIST;
    }

    list_len = strnlen(certificate_list, MAX_INPUT_SIZE);

    ret = verify_list(certificate_list, list_len);

    if (ret) {
        return ERR_INVALID_SIGNATURE;
    }

    if (!strv_length(to_install) && !strv_length(to_remove)) {
        return ERR_NO_INSTRUCTIONS;
    }


    /* Check that the instructions are ok to execute */
    if (to_install) {
        ret = validate_instructions(all_certs, to_install);
        if (ret) {
            return ret;
        }
    }

    if (to_remove) {
        if (to_remove[0] && strncmp("UNINSTALL", to_remove[0], MAX_LINE_LENGTH) == 0) {
            uninstall = true;
            strv_free(to_remove);
            to_remove = NULL;
        } else {
            ret = validate_instructions(all_certs, to_remove);
            if (ret) {
                return ret;
            }
        }
    }

    if (uninstall) {
        /* To uninstall does not have to be verified as it part of the
         * signed list.*/
        to_remove = all_certs;
    } else {
        strv_free(all_certs);
        all_certs = NULL;
    }

#ifdef WIN32
    return write_stores_win (to_install, to_remove, true);
#endif

    /* Make valgrind happy */
    strv_free(to_install);
    strv_free(to_remove);
    free(certificate_list);

    return 0;
}