/*
 * Whitespace rules
 *
 * Copyright (c) 2007 Junio C Hamano
 */

#include "cache.h"
#include "attr.h"

static struct whitespace_rule {
        const char *rule_name;
        unsigned rule_bits;
} whitespace_rule_names[] = {
        { "trailing-space", WS_TRAILING_SPACE },
        { "space-before-tab", WS_SPACE_BEFORE_TAB },
        { "indent-with-non-tab", WS_INDENT_WITH_NON_TAB },
};

unsigned parse_whitespace_rule(const char *string)
{
        unsigned rule = WS_DEFAULT_RULE;

        while (string) {
                int i;
                size_t len;
                const char *ep;
                int negated = 0;

                string = string + strspn(string, ", \t\n\r");
                ep = strchr(string, ',');
                if (!ep)
                        len = strlen(string);
                else
                        len = ep - string;

                if (*string == '-') {
                        negated = 1;
                        string++;
                        len--;
                }
                if (!len)
                        break;
                for (i = 0; i < ARRAY_SIZE(whitespace_rule_names); i++) {
                        if (strncmp(whitespace_rule_names[i].rule_name,
                                    string, len))
                                continue;
                        if (negated)
                                rule &= ~whitespace_rule_names[i].rule_bits;
                        else
                                rule |= whitespace_rule_names[i].rule_bits;
                        break;
                }
                string = ep;
        }
        return rule;
}

static void setup_whitespace_attr_check(struct git_attr_check *check)
{
        static struct git_attr *attr_whitespace;

        if (!attr_whitespace)
                attr_whitespace = git_attr("whitespace", 10);
        check[0].attr = attr_whitespace;
}

unsigned whitespace_rule(const char *pathname)
{
        struct git_attr_check attr_whitespace_rule;

        setup_whitespace_attr_check(&attr_whitespace_rule);
        if (!git_checkattr(pathname, 1, &attr_whitespace_rule)) {
                const char *value;

                value = attr_whitespace_rule.value;
                if (ATTR_TRUE(value)) {
                        /* true (whitespace) */
                        unsigned all_rule = 0;
                        int i;
                        for (i = 0; i < ARRAY_SIZE(whitespace_rule_names); i++)
                                all_rule |= whitespace_rule_names[i].rule_bits;
                        return all_rule;
                } else if (ATTR_FALSE(value)) {
                        /* false (-whitespace) */
                        return 0;
                } else if (ATTR_UNSET(value)) {
                        /* reset to default (!whitespace) */
                        return whitespace_rule_cfg;
                } else {
                        /* string */
                        return parse_whitespace_rule(value);
                }
        } else {
                return whitespace_rule_cfg;
        }
}

/* The returned string should be freed by the caller. */
char *whitespace_error_string(unsigned ws)
{
        struct strbuf err;
        strbuf_init(&err, 0);
        if (ws & WS_TRAILING_SPACE)
                strbuf_addstr(&err, "trailing whitespace");
        if (ws & WS_SPACE_BEFORE_TAB) {
                if (err.len)
                        strbuf_addstr(&err, ", ");
                strbuf_addstr(&err, "space before tab in indent");
        }
        if (ws & WS_INDENT_WITH_NON_TAB) {
                if (err.len)
                        strbuf_addstr(&err, ", ");
                strbuf_addstr(&err, "indent with spaces");
        }
        return strbuf_detach(&err, NULL);
}

/* If stream is non-NULL, emits the line after checking. */
unsigned check_and_emit_line(const char *line, int len, unsigned ws_rule,
                             FILE *stream, const char *set,
                             const char *reset, const char *ws)
{
        unsigned result = 0;
        int written = 0;
        int trailing_whitespace = -1;
        int trailing_newline = 0;
        int i;

        /* Logic is simpler if we temporarily ignore the trailing newline. */
        if (len > 0 && line[len - 1] == '\n') {
                trailing_newline = 1;
                len--;
        }

        /* Check for trailing whitespace. */
        if (ws_rule & WS_TRAILING_SPACE) {
                for (i = len - 1; i >= 0; i--) {
                        if (isspace(line[i])) {
                                trailing_whitespace = i;
                                result |= WS_TRAILING_SPACE;
                        }
                        else
                                break;
                }
        }

        /* Check for space before tab in initial indent. */
        for (i = 0; i < len; i++) {
                if (line[i] == ' ')
                        continue;
                if (line[i] != '\t')
                        break;
                if ((ws_rule & WS_SPACE_BEFORE_TAB) && written < i) {
                        result |= WS_SPACE_BEFORE_TAB;
                        if (stream) {
                                fputs(ws, stream);
                                fwrite(line + written, i - written, 1, stream);
                                fputs(reset, stream);
                        }
                } else if (stream)
                        fwrite(line + written, i - written, 1, stream);
                if (stream)
                        fwrite(line + i, 1, 1, stream);
                written = i + 1;
        }

        /* Check for indent using non-tab. */
        if ((ws_rule & WS_INDENT_WITH_NON_TAB) && i - written >= 8) {
                result |= WS_INDENT_WITH_NON_TAB;
                if (stream) {
                        fputs(ws, stream);
                        fwrite(line + written, i - written, 1, stream);
                        fputs(reset, stream);
                }
                written = i;
        }

        if (stream) {
                /* Now the rest of the line starts at written.
                 * The non-highlighted part ends at trailing_whitespace. */
                if (trailing_whitespace == -1)
                        trailing_whitespace = len;

                /* Emit non-highlighted (middle) segment. */
                if (trailing_whitespace - written > 0) {
                        fputs(set, stream);
                        fwrite(line + written,
                            trailing_whitespace - written, 1, stream);
                        fputs(reset, stream);
                }

                /* Highlight errors in trailing whitespace. */
                if (trailing_whitespace != len) {
                        fputs(ws, stream);
                        fwrite(line + trailing_whitespace,
                            len - trailing_whitespace, 1, stream);
                        fputs(reset, stream);
                }
                if (trailing_newline)
                        fputc('\n', stream);
        }
        return result;
}