#include "cache.h"
#include "credential.h"
#include "string-list.h"
#include "run-command.h"
#include "url.h"

void credential_init(struct credential *c)
{
        memset(c, 0, sizeof(*c));
        c->helpers.strdup_strings = 1;
}

void credential_clear(struct credential *c)
{
        free(c->protocol);
        free(c->host);
        free(c->path);
        free(c->username);
        free(c->password);
        string_list_clear(&c->helpers, 0);

        credential_init(c);
}

int credential_match(const struct credential *want,
                     const struct credential *have)
{
#define CHECK(x) (!want->x || (have->x && !strcmp(want->x, have->x)))
        return CHECK(protocol) &&
               CHECK(host) &&
               CHECK(path) &&
               CHECK(username);
#undef CHECK
}

static int credential_config_callback(const char *var, const char *value,
                                      void *data)
{
        struct credential *c = data;
        const char *key, *dot;

        key = skip_prefix(var, "credential.");
        if (!key)
                return 0;

        if (!value)
                return config_error_nonbool(var);

        dot = strrchr(key, '.');
        if (dot) {
                struct credential want = CREDENTIAL_INIT;
                char *url = xmemdupz(key, dot - key);
                int matched;

                credential_from_url(&want, url);
                matched = credential_match(&want, c);

                credential_clear(&want);
                free(url);

                if (!matched)
                        return 0;
                key = dot + 1;
        }

        if (!strcmp(key, "helper"))
                string_list_append(&c->helpers, value);

        return 0;
}

static void credential_apply_config(struct credential *c)
{
        if (c->configured)
                return;
        git_config(credential_config_callback, c);
        c->configured = 1;
}

static void credential_describe(struct credential *c, struct strbuf *out)
{
        if (!c->protocol)
                return;
        strbuf_addf(out, "%s://", c->protocol);
        if (c->username && *c->username)
                strbuf_addf(out, "%s@", c->username);
        if (c->host)
                strbuf_addstr(out, c->host);
        if (c->path)
                strbuf_addf(out, "/%s", c->path);
}

static char *credential_ask_one(const char *what, struct credential *c)
{
        struct strbuf desc = STRBUF_INIT;
        struct strbuf prompt = STRBUF_INIT;
        char *r;

        credential_describe(c, &desc);
        if (desc.len)
                strbuf_addf(&prompt, "%s for '%s': ", what, desc.buf);
        else
                strbuf_addf(&prompt, "%s: ", what);

        /* FIXME: for usernames, we should do something less magical that
         * actually echoes the characters. However, we need to read from
         * /dev/tty and not stdio, which is not portable (but getpass will do
         * it for us). http.c uses the same workaround. */
        r = git_getpass(prompt.buf);

        strbuf_release(&desc);
        strbuf_release(&prompt);
        return xstrdup(r);
}

static void credential_getpass(struct credential *c)
{
        if (!c->username)
                c->username = credential_ask_one("Username", c);
        if (!c->password)
                c->password = credential_ask_one("Password", c);
}

int credential_read(struct credential *c, FILE *fp)
{
        struct strbuf line = STRBUF_INIT;

        while (strbuf_getline(&line, fp, '\n') != EOF) {
                char *key = line.buf;
                char *value = strchr(key, '=');

                if (!line.len)
                        break;

                if (!value) {
                        warning("invalid credential line: %s", key);
                        strbuf_release(&line);
                        return -1;
                }
                *value++ = '\0';

                if (!strcmp(key, "username")) {
                        free(c->username);
                        c->username = xstrdup(value);
                } else if (!strcmp(key, "password")) {
                        free(c->password);
                        c->password = xstrdup(value);
                } else if (!strcmp(key, "protocol")) {
                        free(c->protocol);
                        c->protocol = xstrdup(value);
                } else if (!strcmp(key, "host")) {
                        free(c->host);
                        c->host = xstrdup(value);
                } else if (!strcmp(key, "path")) {
                        free(c->path);
                        c->path = xstrdup(value);
                }
                /*
                 * Ignore other lines; we don't know what they mean, but
                 * this future-proofs us when later versions of git do
                 * learn new lines, and the helpers are updated to match.
                 */
        }

        strbuf_release(&line);
        return 0;
}

static void credential_write_item(FILE *fp, const char *key, const char *value)
{
        if (!value)
                return;
        fprintf(fp, "%s=%s\n", key, value);
}

static void credential_write(const struct credential *c, FILE *fp)
{
        credential_write_item(fp, "protocol", c->protocol);
        credential_write_item(fp, "host", c->host);
        credential_write_item(fp, "path", c->path);
        credential_write_item(fp, "username", c->username);
        credential_write_item(fp, "password", c->password);
}

static int run_credential_helper(struct credential *c,
                                 const char *cmd,
                                 int want_output)
{
        struct child_process helper;
        const char *argv[] = { NULL, NULL };
        FILE *fp;

        memset(&helper, 0, sizeof(helper));
        argv[0] = cmd;
        helper.argv = argv;
        helper.use_shell = 1;
        helper.in = -1;
        if (want_output)
                helper.out = -1;
        else
                helper.no_stdout = 1;

        if (start_command(&helper) < 0)
                return -1;

        fp = xfdopen(helper.in, "w");
        credential_write(c, fp);
        fclose(fp);

        if (want_output) {
                int r;
                fp = xfdopen(helper.out, "r");
                r = credential_read(c, fp);
                fclose(fp);
                if (r < 0) {
                        finish_command(&helper);
                        return -1;
                }
        }

        if (finish_command(&helper))
                return -1;
        return 0;
}

static int credential_do(struct credential *c, const char *helper,
                         const char *operation)
{
        struct strbuf cmd = STRBUF_INIT;
        int r;

        if (helper[0] == '!')
                strbuf_addstr(&cmd, helper + 1);
        else if (is_absolute_path(helper))
                strbuf_addstr(&cmd, helper);
        else
                strbuf_addf(&cmd, "git credential-%s", helper);

        strbuf_addf(&cmd, " %s", operation);
        r = run_credential_helper(c, cmd.buf, !strcmp(operation, "get"));

        strbuf_release(&cmd);
        return r;
}

void credential_fill(struct credential *c)
{
        int i;

        if (c->username && c->password)
                return;

        credential_apply_config(c);

        for (i = 0; i < c->helpers.nr; i++) {
                credential_do(c, c->helpers.items[i].string, "get");
                if (c->username && c->password)
                        return;
        }

        credential_getpass(c);
        if (!c->username && !c->password)
                die("unable to get password from user");
}

void credential_approve(struct credential *c)
{
        int i;

        if (c->approved)
                return;
        if (!c->username || !c->password)
                return;

        credential_apply_config(c);

        for (i = 0; i < c->helpers.nr; i++)
                credential_do(c, c->helpers.items[i].string, "store");
        c->approved = 1;
}

void credential_reject(struct credential *c)
{
        int i;

        credential_apply_config(c);

        for (i = 0; i < c->helpers.nr; i++)
                credential_do(c, c->helpers.items[i].string, "erase");

        free(c->username);
        c->username = NULL;
        free(c->password);
        c->password = NULL;
        c->approved = 0;
}

void credential_from_url(struct credential *c, const char *url)
{
        const char *at, *colon, *cp, *slash, *host, *proto_end;

        credential_clear(c);

        /*
         * Match one of:
         *   (1) proto://<host>/...
         *   (2) proto://<user>@<host>/...
         *   (3) proto://<user>:<pass>@<host>/...
         */
        proto_end = strstr(url, "://");
        if (!proto_end)
                return;
        cp = proto_end + 3;
        at = strchr(cp, '@');
        colon = strchr(cp, ':');
        slash = strchrnul(cp, '/');

        if (!at || slash <= at) {
                /* Case (1) */
                host = cp;
        }
        else if (!colon || at <= colon) {
                /* Case (2) */
                c->username = url_decode_mem(cp, at - cp);
                host = at + 1;
        } else {
                /* Case (3) */
                c->username = url_decode_mem(cp, colon - cp);
                c->password = url_decode_mem(colon + 1, at - (colon + 1));
                host = at + 1;
        }

        if (proto_end - url > 0)
                c->protocol = xmemdupz(url, proto_end - url);
        if (slash - host > 0)
                c->host = url_decode_mem(host, slash - host);
        /* Trim leading and trailing slashes from path */
        while (*slash == '/')
                slash++;
        if (*slash) {
                char *p;
                c->path = url_decode(slash);
                p = c->path + strlen(c->path) - 1;
                while (p > c->path && *p == '/')
                        *p-- = '\0';
        }
}