/*

 * Whitespace rules

 *

 * Copyright (c) 2007 Junio C Hamano

 */

#include "git-compat-util.h"

#include "attr.h"

#include "strbuf.h"

#include "ws.h"

unsigned whitespace_rule_cfg = WS_DEFAULT_RULE;

static struct whitespace_rule {

  const char *rule_name;

  unsigned rule_bits;

  unsigned loosens_error:1,

    exclude_default:1;

} whitespace_rule_names[] = {

  { "trailing-space", WS_TRAILING_SPACE, 0 },

  { "space-before-tab", WS_SPACE_BEFORE_TAB, 0 },

  { "indent-with-non-tab", WS_INDENT_WITH_NON_TAB, 0 },

  { "cr-at-eol", WS_CR_AT_EOL, 1 },

  { "blank-at-eol", WS_BLANK_AT_EOL, 0 },

  { "blank-at-eof", WS_BLANK_AT_EOF, 0 },

  { "tab-in-indent", WS_TAB_IN_INDENT, 0, 1 },

};

unsigned parse_whitespace_rule(const char *string)

{

  unsigned rule = WS_DEFAULT_RULE;

  while (string) {

    int i;

    size_t len;

    const char *ep;

    const char *arg;

    int negated = 0;

    string = string + strspn(string, ", \t\n\r");

    ep = strchrnul(string, ',');

    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;

    }

    if (skip_prefix(string, "tabwidth=", &arg)) {

      unsigned tabwidth = atoi(arg);

      if (0 < tabwidth && tabwidth < 0100) {

        rule &= ~WS_TAB_WIDTH_MASK;

        rule |= tabwidth;

      }

      else

        warning("tabwidth %.*s out of range",

          (int)(ep - arg), arg);

    }

    string = ep;

  }

  if (rule & WS_TAB_IN_INDENT && rule & WS_INDENT_WITH_NON_TAB)

    die("cannot enforce both tab-in-indent and indent-with-non-tab");

  return rule;

}

unsigned whitespace_rule(struct index_state *istate, const char *pathname)

{

  static struct attr_check *attr_whitespace_rule;

  const char *value;

  if (!attr_whitespace_rule)

    attr_whitespace_rule = attr_check_initl("whitespace", NULL);

  git_check_attr(istate, pathname, attr_whitespace_rule);

  value = attr_whitespace_rule->items[0].value;

  if (ATTR_TRUE(value)) {

    /* true (whitespace) */

    unsigned all_rule = ws_tab_width(whitespace_rule_cfg);

    int i;

    for (i = 0; i < ARRAY_SIZE(whitespace_rule_names); i++)

      if (!whitespace_rule_names[i].loosens_error &&

          !whitespace_rule_names[i].exclude_default)

        all_rule |= whitespace_rule_names[i].rule_bits;

    return all_rule;

  } else if (ATTR_FALSE(value)) {

    /* false (-whitespace) */

    return ws_tab_width(whitespace_rule_cfg);

  } else if (ATTR_UNSET(value)) {

    /* reset to default (!whitespace) */

    return whitespace_rule_cfg;

  } else {

    /* string */

    return parse_whitespace_rule(value);

  }

}

/* The returned string should be freed by the caller. */

char *whitespace_error_string(unsigned ws)

{

  struct strbuf err = STRBUF_INIT;

  if ((ws & WS_TRAILING_SPACE) == WS_TRAILING_SPACE)

    strbuf_addstr(&err, "trailing whitespace");

  else {

    if (ws & WS_BLANK_AT_EOL)

      strbuf_addstr(&err, "trailing whitespace");

    if (ws & WS_BLANK_AT_EOF) {

      if (err.len)

        strbuf_addstr(&err, ", ");

      strbuf_addstr(&err, "new blank line at EOF");

    }

  }

  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");

  }

  if (ws & WS_TAB_IN_INDENT) {

    if (err.len)

      strbuf_addstr(&err, ", ");

    strbuf_addstr(&err, "tab in indent");

  }

  return strbuf_detach(&err, NULL);

}

/* If stream is non-NULL, emits the line after checking. */

static unsigned ws_check_emit_1(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 trailing_carriage_return = 0;

  int i;

  /* Logic is simpler if we temporarily ignore the trailing newline. */

  if (len > 0 && line[len - 1] == '\n') {

    trailing_newline = 1;

    len--;

  }

  if ((ws_rule & WS_CR_AT_EOL) &&

      len > 0 && line[len - 1] == '\r') {

    trailing_carriage_return = 1;

    len--;

  }

  /* Check for trailing whitespace. */

  if (ws_rule & WS_BLANK_AT_EOL) {

    for (i = len - 1; i >= 0; i--) {

      if (isspace(line[i])) {

        trailing_whitespace = i;

        result |= WS_BLANK_AT_EOL;

      }

      else

        break;

    }

  }

  if (trailing_whitespace == -1)

    trailing_whitespace = len;

  /* Check indentation */

  for (i = 0; i < trailing_whitespace; 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);

        fwrite(line + i, 1, 1, stream);

      }

    } else if (ws_rule & WS_TAB_IN_INDENT) {

      result |= WS_TAB_IN_INDENT;

      if (stream) {

        fwrite(line + written, i - written, 1, stream);

        fputs(ws, stream);

        fwrite(line + i, 1, 1, stream);

        fputs(reset, stream);

      }

    } else if (stream) {

      fwrite(line + written, i - written + 1, 1, stream);

    }

    written = i + 1;

  }

  /* Check for indent using non-tab. */

  if ((ws_rule & WS_INDENT_WITH_NON_TAB) && i - written >= ws_tab_width(ws_rule)) {

    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".

     */

    /* 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_carriage_return)

      fputc('\r', stream);

    if (trailing_newline)

      fputc('\n', stream);

  }

  return result;

}

void ws_check_emit(const char *line, int len, unsigned ws_rule,

       FILE *stream, const char *set,

       const char *reset, const char *ws)

{

  (void)ws_check_emit_1(line, len, ws_rule, stream, set, reset, ws);

}

unsigned ws_check(const char *line, int len, unsigned ws_rule)

{

  return ws_check_emit_1(line, len, ws_rule, NULL, NULL, NULL, NULL);

}

int ws_blank_line(const char *line, int len)

{

  /*

   * We _might_ want to treat CR differently from other

   * whitespace characters when ws_rule has WS_CR_AT_EOL, but

   * for now we just use this stupid definition.

   */

  while (len-- > 0) {

    if (!isspace(*line))

      return 0;

    line++;

  }

  return 1;

}

/* Copy the line onto the end of the strbuf while fixing whitespaces */

void ws_fix_copy(struct strbuf *dst, const char *src, int len, unsigned ws_rule, int *error_count)

{

  /*

   * len is number of bytes to be copied from src, starting

   * at src.  Typically src[len-1] is '\n', unless this is

   * the incomplete last line.

   */

  int i;

  int add_nl_to_tail = 0;

  int add_cr_to_tail = 0;

  int fixed = 0;

  int last_tab_in_indent = -1;

  int last_space_in_indent = -1;

  int need_fix_leading_space = 0;

  /*

   * Strip trailing whitespace

   */

  if (ws_rule & WS_BLANK_AT_EOL) {

    if (0 < len && src[len - 1] == '\n') {

      add_nl_to_tail = 1;

      len--;

      if (0 < len && src[len - 1] == '\r') {

        add_cr_to_tail = !!(ws_rule & WS_CR_AT_EOL);

        len--;

      }

    }

    if (0 < len && isspace(src[len - 1])) {

      while (0 < len && isspace(src[len-1]))

        len--;

      fixed = 1;

    }

  }

  /*

   * Check leading whitespaces (indent)

   */

  for (i = 0; i < len; i++) {

    char ch = src[i];

    if (ch == '\t') {

      last_tab_in_indent = i;

      if ((ws_rule & WS_SPACE_BEFORE_TAB) &&

          0 <= last_space_in_indent)

          need_fix_leading_space = 1;

    } else if (ch == ' ') {

      last_space_in_indent = i;

      if ((ws_rule & WS_INDENT_WITH_NON_TAB) &&

          ws_tab_width(ws_rule) <= i - last_tab_in_indent)

        need_fix_leading_space = 1;

    } else

      break;

  }

  if (need_fix_leading_space) {

    /* Process indent ourselves */

    int consecutive_spaces = 0;

    int last = last_tab_in_indent + 1;

    if (ws_rule & WS_INDENT_WITH_NON_TAB) {

      /* have "last" point at one past the indent */

      if (last_tab_in_indent < last_space_in_indent)

        last = last_space_in_indent + 1;

      else

        last = last_tab_in_indent + 1;

    }

    /*

     * between src[0..last-1], strip the funny spaces,

     * updating them to tab as needed.

     */

    for (i = 0; i < last; i++) {

      char ch = src[i];

      if (ch != ' ') {

        consecutive_spaces = 0;

        strbuf_addch(dst, ch);

      } else {

        consecutive_spaces++;

        if (consecutive_spaces == ws_tab_width(ws_rule)) {

          strbuf_addch(dst, '\t');

          consecutive_spaces = 0;

        }

      }

    }

    while (0 < consecutive_spaces--)

      strbuf_addch(dst, ' ');

    len -= last;

    src += last;

    fixed = 1;

  } else if ((ws_rule & WS_TAB_IN_INDENT) && last_tab_in_indent >= 0) {

    /* Expand tabs into spaces */

    int start = dst->len;

    int last = last_tab_in_indent + 1;

    for (i = 0; i < last; i++) {

      if (src[i] == '\t')

        do {

          strbuf_addch(dst, ' ');

        } while ((dst->len - start) % ws_tab_width(ws_rule));

      else

        strbuf_addch(dst, src[i]);

    }

    len -= last;

    src += last;

    fixed = 1;

  }

  strbuf_add(dst, src, len);

  if (add_cr_to_tail)

    strbuf_addch(dst, '\r');

  if (add_nl_to_tail)

    strbuf_addch(dst, '\n');

  if (fixed && error_count)

    (*error_count)++;

}