/*
 * GIT - The information manager from hell
 *
 * Copyright (C) Linus Torvalds, 2005
 * Copyright (C) Johannes Schindelin, 2005
 *
 */
#include "util.h"
#include "cache.h"
#include "exec_cmd.h"

#define MAXNAME (256)

static FILE *config_file;
static const char *config_file_name;
static int config_linenr;
static int config_file_eof;

const char *config_exclusive_filename = NULL;

static int get_next_char(void)
{
        int c;
        FILE *f;

        c = '\n';
        if ((f = config_file) != NULL) {
                c = fgetc(f);
                if (c == '\r') {
                        /* DOS like systems */
                        c = fgetc(f);
                        if (c != '\n') {
                                ungetc(c, f);
                                c = '\r';
                        }
                }
                if (c == '\n')
                        config_linenr++;
                if (c == EOF) {
                        config_file_eof = 1;
                        c = '\n';
                }
        }
        return c;
}

static char *parse_value(void)
{
        static char value[1024];
        int quote = 0, comment = 0, space = 0;
        size_t len = 0;

        for (;;) {
                int c = get_next_char();

                if (len >= sizeof(value) - 1)
                        return NULL;
                if (c == '\n') {
                        if (quote)
                                return NULL;
                        value[len] = 0;
                        return value;
                }
                if (comment)
                        continue;
                if (isspace(c) && !quote) {
                        space = 1;
                        continue;
                }
                if (!quote) {
                        if (c == ';' || c == '#') {
                                comment = 1;
                                continue;
                        }
                }
                if (space) {
                        if (len)
                                value[len++] = ' ';
                        space = 0;
                }
                if (c == '\\') {
                        c = get_next_char();
                        switch (c) {
                        case '\n':
                                continue;
                        case 't':
                                c = '\t';
                                break;
                        case 'b':
                                c = '\b';
                                break;
                        case 'n':
                                c = '\n';
                                break;
                        /* Some characters escape as themselves */
                        case '\\': case '"':
                                break;
                        /* Reject unknown escape sequences */
                        default:
                                return NULL;
                        }
                        value[len++] = c;
                        continue;
                }
                if (c == '"') {
                        quote = 1-quote;
                        continue;
                }
                value[len++] = c;
        }
}

static inline int iskeychar(int c)
{
        return isalnum(c) || c == '-';
}

static int get_value(config_fn_t fn, void *data, char *name, unsigned int len)
{
        int c;
        char *value;

        /* Get the full name */
        for (;;) {
                c = get_next_char();
                if (config_file_eof)
                        break;
                if (!iskeychar(c))
                        break;
                name[len++] = tolower(c);
                if (len >= MAXNAME)
                        return -1;
        }
        name[len] = 0;
        while (c == ' ' || c == '\t')
                c = get_next_char();

        value = NULL;
        if (c != '\n') {
                if (c != '=')
                        return -1;
                value = parse_value();
                if (!value)
                        return -1;
        }
        return fn(name, value, data);
}

static int get_extended_base_var(char *name, int baselen, int c)
{
        do {
                if (c == '\n')
                        return -1;
                c = get_next_char();
        } while (isspace(c));

        /* We require the format to be '[base "extension"]' */
        if (c != '"')
                return -1;
        name[baselen++] = '.';

        for (;;) {
                int ch = get_next_char();

                if (ch == '\n')
                        return -1;
                if (ch == '"')
                        break;
                if (ch == '\\') {
                        ch = get_next_char();
                        if (ch == '\n')
                                return -1;
                }
                name[baselen++] = ch;
                if (baselen > MAXNAME / 2)
                        return -1;
        }

        /* Final ']' */
        if (get_next_char() != ']')
                return -1;
        return baselen;
}

static int get_base_var(char *name)
{
        int baselen = 0;

        for (;;) {
                int c = get_next_char();
                if (config_file_eof)
                        return -1;
                if (c == ']')
                        return baselen;
                if (isspace(c))
                        return get_extended_base_var(name, baselen, c);
                if (!iskeychar(c) && c != '.')
                        return -1;
                if (baselen > MAXNAME / 2)
                        return -1;
                name[baselen++] = tolower(c);
        }
}

static int perf_parse_file(config_fn_t fn, void *data)
{
        int comment = 0;
        int baselen = 0;
        static char var[MAXNAME];

        /* U+FEFF Byte Order Mark in UTF8 */
        static const unsigned char *utf8_bom = (unsigned char *) "\xef\xbb\xbf";
        const unsigned char *bomptr = utf8_bom;

        for (;;) {
                int c = get_next_char();
                if (bomptr && *bomptr) {
                        /* We are at the file beginning; skip UTF8-encoded BOM
                         * if present. Sane editors won't put this in on their
                         * own, but e.g. Windows Notepad will do it happily. */
                        if ((unsigned char) c == *bomptr) {
                                bomptr++;
                                continue;
                        } else {
                                /* Do not tolerate partial BOM. */
                                if (bomptr != utf8_bom)
                                        break;
                                /* No BOM at file beginning. Cool. */
                                bomptr = NULL;
                        }
                }
                if (c == '\n') {
                        if (config_file_eof)
                                return 0;
                        comment = 0;
                        continue;
                }
                if (comment || isspace(c))
                        continue;
                if (c == '#' || c == ';') {
                        comment = 1;
                        continue;
                }
                if (c == '[') {
                        baselen = get_base_var(var);
                        if (baselen <= 0)
                                break;
                        var[baselen++] = '.';
                        var[baselen] = 0;
                        continue;
                }
                if (!isalpha(c))
                        break;
                var[baselen] = tolower(c);
                if (get_value(fn, data, var, baselen+1) < 0)
                        break;
        }
        die("bad config file line %d in %s", config_linenr, config_file_name);
}

static int parse_unit_factor(const char *end, unsigned long *val)
{
        if (!*end)
                return 1;
        else if (!strcasecmp(end, "k")) {
                *val *= 1024;
                return 1;
        }
        else if (!strcasecmp(end, "m")) {
                *val *= 1024 * 1024;
                return 1;
        }
        else if (!strcasecmp(end, "g")) {
                *val *= 1024 * 1024 * 1024;
                return 1;
        }
        return 0;
}

static int perf_parse_long(const char *value, long *ret)
{
        if (value && *value) {
                char *end;
                long val = strtol(value, &end, 0);
                unsigned long factor = 1;
                if (!parse_unit_factor(end, &factor))
                        return 0;
                *ret = val * factor;
                return 1;
        }
        return 0;
}

int perf_parse_ulong(const char *value, unsigned long *ret)
{
        if (value && *value) {
                char *end;
                unsigned long val = strtoul(value, &end, 0);
                if (!parse_unit_factor(end, &val))
                        return 0;
                *ret = val;
                return 1;
        }
        return 0;
}

static void die_bad_config(const char *name)
{
        if (config_file_name)
                die("bad config value for '%s' in %s", name, config_file_name);
        die("bad config value for '%s'", name);
}

int perf_config_int(const char *name, const char *value)
{
        long ret = 0;
        if (!perf_parse_long(value, &ret))
                die_bad_config(name);
        return ret;
}

unsigned long perf_config_ulong(const char *name, const char *value)
{
        unsigned long ret;
        if (!perf_parse_ulong(value, &ret))
                die_bad_config(name);
        return ret;
}

int perf_config_bool_or_int(const char *name, const char *value, int *is_bool)
{
        *is_bool = 1;
        if (!value)
                return 1;
        if (!*value)
                return 0;
        if (!strcasecmp(value, "true") || !strcasecmp(value, "yes") || !strcasecmp(value, "on"))
                return 1;
        if (!strcasecmp(value, "false") || !strcasecmp(value, "no") || !strcasecmp(value, "off"))
                return 0;
        *is_bool = 0;
        return perf_config_int(name, value);
}

int perf_config_bool(const char *name, const char *value)
{
        int discard;
        return !!perf_config_bool_or_int(name, value, &discard);
}

int perf_config_string(const char **dest, const char *var, const char *value)
{
        if (!value)
                return config_error_nonbool(var);
        *dest = strdup(value);
        return 0;
}

static int perf_default_core_config(const char *var __used, const char *value __used)
{
        /* Add other config variables here and to Documentation/config.txt. */
        return 0;
}

int perf_default_config(const char *var, const char *value, void *dummy __used)
{
        if (!prefixcmp(var, "core."))
                return perf_default_core_config(var, value);

        /* Add other config variables here and to Documentation/config.txt. */
        return 0;
}

int perf_config_from_file(config_fn_t fn, const char *filename, void *data)
{
        int ret;
        FILE *f = fopen(filename, "r");

        ret = -1;
        if (f) {
                config_file = f;
                config_file_name = filename;
                config_linenr = 1;
                config_file_eof = 0;
                ret = perf_parse_file(fn, data);
                fclose(f);
                config_file_name = NULL;
        }
        return ret;
}

const char *perf_etc_perfconfig(void)
{
        static const char *system_wide;
        if (!system_wide)
                system_wide = system_path(ETC_PERFCONFIG);
        return system_wide;
}

static int perf_env_bool(const char *k, int def)
{
        const char *v = getenv(k);
        return v ? perf_config_bool(k, v) : def;
}

int perf_config_system(void)
{
        return !perf_env_bool("PERF_CONFIG_NOSYSTEM", 0);
}

int perf_config_global(void)
{
        return !perf_env_bool("PERF_CONFIG_NOGLOBAL", 0);
}

int perf_config(config_fn_t fn, void *data)
{
        int ret = 0, found = 0;
        char *repo_config = NULL;
        const char *home = NULL;

        /* Setting $PERF_CONFIG makes perf read _only_ the given config file. */
        if (config_exclusive_filename)
                return perf_config_from_file(fn, config_exclusive_filename, data);
        if (perf_config_system() && !access(perf_etc_perfconfig(), R_OK)) {
                ret += perf_config_from_file(fn, perf_etc_perfconfig(),
                                            data);
                found += 1;
        }

        home = getenv("HOME");
        if (perf_config_global() && home) {
                char *user_config = strdup(mkpath("%s/.perfconfig", home));
                if (!access(user_config, R_OK)) {
                        ret += perf_config_from_file(fn, user_config, data);
                        found += 1;
                }
                free(user_config);
        }

        repo_config = perf_pathdup("config");
        if (!access(repo_config, R_OK)) {
                ret += perf_config_from_file(fn, repo_config, data);
                found += 1;
        }
        free(repo_config);
        if (found == 0)
                return -1;
        return ret;
}

/*
 * Find all the stuff for perf_config_set() below.
 */

#define MAX_MATCHES 512

static struct {
        int baselen;
        char* key;
        int do_not_match;
        regex_t* value_regex;
        int multi_replace;
        size_t offset[MAX_MATCHES];
        enum { START, SECTION_SEEN, SECTION_END_SEEN, KEY_SEEN } state;
        int seen;
} store;

static int matches(const char* key, const char* value)
{
        return !strcmp(key, store.key) &&
                (store.value_regex == NULL ||
                 (store.do_not_match ^
                  !regexec(store.value_regex, value, 0, NULL, 0)));
}

static int store_aux(const char* key, const char* value, void *cb __used)
{
        int section_len;
        const char *ep;

        switch (store.state) {
        case KEY_SEEN:
                if (matches(key, value)) {
                        if (store.seen == 1 && store.multi_replace == 0) {
                                warning("%s has multiple values", key);
                        } else if (store.seen >= MAX_MATCHES) {
                                error("too many matches for %s", key);
                                return 1;
                        }

                        store.offset[store.seen] = ftell(config_file);
                        store.seen++;
                }
                break;
        case SECTION_SEEN:
                /*
                 * What we are looking for is in store.key (both
                 * section and var), and its section part is baselen
                 * long.  We found key (again, both section and var).
                 * We would want to know if this key is in the same
                 * section as what we are looking for.  We already
                 * know we are in the same section as what should
                 * hold store.key.
                 */
                ep = strrchr(key, '.');
                section_len = ep - key;

                if ((section_len != store.baselen) ||
                    memcmp(key, store.key, section_len+1)) {
                        store.state = SECTION_END_SEEN;
                        break;
                }

                /*
                 * Do not increment matches: this is no match, but we
                 * just made sure we are in the desired section.
                 */
                store.offset[store.seen] = ftell(config_file);
                /* fallthru */
        case SECTION_END_SEEN:
        case START:
                if (matches(key, value)) {
                        store.offset[store.seen] = ftell(config_file);
                        store.state = KEY_SEEN;
                        store.seen++;
                } else {
                        if (strrchr(key, '.') - key == store.baselen &&
                              !strncmp(key, store.key, store.baselen)) {
                                        store.state = SECTION_SEEN;
                                        store.offset[store.seen] = ftell(config_file);
                        }
                }
        default:
                break;
        }
        return 0;
}

static int store_write_section(int fd, const char* key)
{
        const char *dot;
        int i, success;
        struct strbuf sb = STRBUF_INIT;

        dot = memchr(key, '.', store.baselen);
        if (dot) {
                strbuf_addf(&sb, "[%.*s \"", (int)(dot - key), key);
                for (i = dot - key + 1; i < store.baselen; i++) {
                        if (key[i] == '"' || key[i] == '\\')
                                strbuf_addch(&sb, '\\');
                        strbuf_addch(&sb, key[i]);
                }
                strbuf_addstr(&sb, "\"]\n");
        } else {
                strbuf_addf(&sb, "[%.*s]\n", store.baselen, key);
        }

        success = (write_in_full(fd, sb.buf, sb.len) == (ssize_t)sb.len);
        strbuf_release(&sb);

        return success;
}

static int store_write_pair(int fd, const char* key, const char* value)
{
        int i, success;
        int length = strlen(key + store.baselen + 1);
        const char *quote = "";
        struct strbuf sb = STRBUF_INIT;

        /*
         * Check to see if the value needs to be surrounded with a dq pair.
         * Note that problematic characters are always backslash-quoted; this
         * check is about not losing leading or trailing SP and strings that
         * follow beginning-of-comment characters (i.e. ';' and '#') by the
         * configuration parser.
         */
        if (value[0] == ' ')
                quote = "\"";
        for (i = 0; value[i]; i++)
                if (value[i] == ';' || value[i] == '#')
                        quote = "\"";
        if (i && value[i - 1] == ' ')
                quote = "\"";

        strbuf_addf(&sb, "\t%.*s = %s",
                    length, key + store.baselen + 1, quote);

        for (i = 0; value[i]; i++)
                switch (value[i]) {
                case '\n':
                        strbuf_addstr(&sb, "\\n");
                        break;
                case '\t':
                        strbuf_addstr(&sb, "\\t");
                        break;
                case '"':
                case '\\':
                        strbuf_addch(&sb, '\\');
                default:
                        strbuf_addch(&sb, value[i]);
                        break;
                }
        strbuf_addf(&sb, "%s\n", quote);

        success = (write_in_full(fd, sb.buf, sb.len) == (ssize_t)sb.len);
        strbuf_release(&sb);

        return success;
}

static ssize_t find_beginning_of_line(const char* contents, size_t size,
        size_t offset_, int* found_bracket)
{
        size_t equal_offset = size, bracket_offset = size;
        ssize_t offset;

contline:
        for (offset = offset_-2; offset > 0
                        && contents[offset] != '\n'; offset--)
                switch (contents[offset]) {
                        case '=': equal_offset = offset; break;
                        case ']': bracket_offset = offset; break;
                        default: break;
                }
        if (offset > 0 && contents[offset-1] == '\\') {
                offset_ = offset;
                goto contline;
        }
        if (bracket_offset < equal_offset) {
                *found_bracket = 1;
                offset = bracket_offset+1;
        } else
                offset++;

        return offset;
}

int perf_config_set(const char* key, const char* value)
{
        return perf_config_set_multivar(key, value, NULL, 0);
}

/*
 * If value==NULL, unset in (remove from) config,
 * if value_regex!=NULL, disregard key/value pairs where value does not match.
 * if multi_replace==0, nothing, or only one matching key/value is replaced,
 *     else all matching key/values (regardless how many) are removed,
 *     before the new pair is written.
 *
 * Returns 0 on success.
 *
 * This function does this:
 *
 * - it locks the config file by creating ".perf/config.lock"
 *
 * - it then parses the config using store_aux() as validator to find
 *   the position on the key/value pair to replace. If it is to be unset,
 *   it must be found exactly once.
 *
 * - the config file is mmap()ed and the part before the match (if any) is
 *   written to the lock file, then the changed part and the rest.
 *
 * - the config file is removed and the lock file rename()d to it.
 *
 */
int perf_config_set_multivar(const char* key, const char* value,
        const char* value_regex, int multi_replace)
{
        int i, dot;
        int fd = -1, in_fd;
        int ret = 0;
        char* config_filename;
        const char* last_dot = strrchr(key, '.');

        if (config_exclusive_filename)
                config_filename = strdup(config_exclusive_filename);
        else
                config_filename = perf_pathdup("config");

        /*
         * Since "key" actually contains the section name and the real
         * key name separated by a dot, we have to know where the dot is.
         */

        if (last_dot == NULL) {
                error("key does not contain a section: %s", key);
                ret = 2;
                goto out_free;
        }
        store.baselen = last_dot - key;

        store.multi_replace = multi_replace;

        /*
         * Validate the key and while at it, lower case it for matching.
         */
        store.key = malloc(strlen(key) + 1);
        dot = 0;
        for (i = 0; key[i]; i++) {
                unsigned char c = key[i];
                if (c == '.')
                        dot = 1;
                /* Leave the extended basename untouched.. */
                if (!dot || i > store.baselen) {
                        if (!iskeychar(c) || (i == store.baselen+1 && !isalpha(c))) {
                                error("invalid key: %s", key);
                                free(store.key);
                                ret = 1;
                                goto out_free;
                        }
                        c = tolower(c);
                } else if (c == '\n') {
                        error("invalid key (newline): %s", key);
                        free(store.key);
                        ret = 1;
                        goto out_free;
                }
                store.key[i] = c;
        }
        store.key[i] = 0;

        /*
         * If .perf/config does not exist yet, write a minimal version.
         */
        in_fd = open(config_filename, O_RDONLY);
        if ( in_fd < 0 ) {
                free(store.key);

                if ( ENOENT != errno ) {
                        error("opening %s: %s", config_filename,
                              strerror(errno));
                        ret = 3; /* same as "invalid config file" */
                        goto out_free;
                }
                /* if nothing to unset, error out */
                if (value == NULL) {
                        ret = 5;
                        goto out_free;
                }

                store.key = (char*)key;
                if (!store_write_section(fd, key) ||
                    !store_write_pair(fd, key, value))
                        goto write_err_out;
        } else {
                struct stat st;
                char *contents;
                ssize_t contents_sz, copy_begin, copy_end;
                int new_line = 0;

                if (value_regex == NULL)
                        store.value_regex = NULL;
                else {
                        if (value_regex[0] == '!') {
                                store.do_not_match = 1;
                                value_regex++;
                        } else
                                store.do_not_match = 0;

                        store.value_regex = (regex_t*)malloc(sizeof(regex_t));
                        if (regcomp(store.value_regex, value_regex,
                                        REG_EXTENDED)) {
                                error("invalid pattern: %s", value_regex);
                                free(store.value_regex);
                                ret = 6;
                                goto out_free;
                        }
                }

                store.offset[0] = 0;
                store.state = START;
                store.seen = 0;

                /*
                 * After this, store.offset will contain the *end* offset
                 * of the last match, or remain at 0 if no match was found.
                 * As a side effect, we make sure to transform only a valid
                 * existing config file.
                 */
                if (perf_config_from_file(store_aux, config_filename, NULL)) {
                        error("invalid config file %s", config_filename);
                        free(store.key);
                        if (store.value_regex != NULL) {
                                regfree(store.value_regex);
                                free(store.value_regex);
                        }
                        ret = 3;
                        goto out_free;
                }

                free(store.key);
                if (store.value_regex != NULL) {
                        regfree(store.value_regex);
                        free(store.value_regex);
                }

                /* if nothing to unset, or too many matches, error out */
                if ((store.seen == 0 && value == NULL) ||
                                (store.seen > 1 && multi_replace == 0)) {
                        ret = 5;
                        goto out_free;
                }

                fstat(in_fd, &st);
                contents_sz = xsize_t(st.st_size);
                contents = mmap(NULL, contents_sz, PROT_READ,
                        MAP_PRIVATE, in_fd, 0);
                close(in_fd);

                if (store.seen == 0)
                        store.seen = 1;

                for (i = 0, copy_begin = 0; i < store.seen; i++) {
                        if (store.offset[i] == 0) {
                                store.offset[i] = copy_end = contents_sz;
                        } else if (store.state != KEY_SEEN) {
                                copy_end = store.offset[i];
                        } else
                                copy_end = find_beginning_of_line(
                                        contents, contents_sz,
                                        store.offset[i]-2, &new_line);

                        if (copy_end > 0 && contents[copy_end-1] != '\n')
                                new_line = 1;

                        /* write the first part of the config */
                        if (copy_end > copy_begin) {
                                if (write_in_full(fd, contents + copy_begin,
                                                  copy_end - copy_begin) <
                                    copy_end - copy_begin)
                                        goto write_err_out;
                                if (new_line &&
                                    write_in_full(fd, "\n", 1) != 1)
                                        goto write_err_out;
                        }
                        copy_begin = store.offset[i];
                }

                /* write the pair (value == NULL means unset) */
                if (value != NULL) {
                        if (store.state == START) {
                                if (!store_write_section(fd, key))
                                        goto write_err_out;
                        }
                        if (!store_write_pair(fd, key, value))
                                goto write_err_out;
                }

                /* write the rest of the config */
                if (copy_begin < contents_sz)
                        if (write_in_full(fd, contents + copy_begin,
                                          contents_sz - copy_begin) <
                            contents_sz - copy_begin)
                                goto write_err_out;

                munmap(contents, contents_sz);
        }

        ret = 0;

out_free:
        free(config_filename);
        return ret;

write_err_out:
        goto out_free;

}

/*
 * Call this to report error for your variable that should not
 * get a boolean value (i.e. "[my] var" means "true").
 */
int config_error_nonbool(const char *var)
{
        return error("Missing value for '%s'", var);
}