99 lines
2.1 KiB
Go
99 lines
2.1 KiB
Go
// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
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// See LICENSE.txt for license information.
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package notifymentions
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import "strings"
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const (
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defPrefixLines = 2
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defPrefixMaxChars = 100
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defSuffixLines = 2
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defSuffixMaxChars = 100
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)
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type limits struct {
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prefixLines int
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prefixMaxChars int
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suffixLines int
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suffixMaxChars int
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}
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func newLimits() limits {
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return limits{
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prefixLines: defPrefixLines,
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prefixMaxChars: defPrefixMaxChars,
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suffixLines: defSuffixLines,
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suffixMaxChars: defSuffixMaxChars,
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}
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}
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// extractText returns all or a subset of the input string, such that
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// no more than `prefixLines` lines preceding the mention and `suffixLines`
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// lines after the mention are returned, and no more than approx
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// prefixMaxChars+suffixMaxChars are returned.
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func extractText(s string, mention string, limits limits) string {
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if !strings.HasPrefix(mention, "@") {
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mention = "@" + mention
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}
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lines := strings.Split(s, "\n")
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// find first line with mention
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found := -1
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for i, l := range lines {
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if strings.Contains(l, mention) {
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found = i
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break
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}
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}
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if found == -1 {
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return ""
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}
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prefix := safeConcat(lines, found-limits.prefixLines, found)
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suffix := safeConcat(lines, found+1, found+limits.suffixLines+1)
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combined := strings.TrimSpace(strings.Join([]string{prefix, lines[found], suffix}, "\n"))
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// find mention position within
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pos := strings.Index(combined, mention)
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pos = max(pos, 0)
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return safeSubstr(combined, pos-limits.prefixMaxChars, pos+limits.suffixMaxChars)
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}
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func safeConcat(lines []string, start int, end int) string {
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count := len(lines)
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start = min(max(start, 0), count)
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end = min(max(end, start), count)
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var sb strings.Builder
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for i := start; i < end; i++ {
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if lines[i] != "" {
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sb.WriteString(lines[i])
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sb.WriteByte('\n')
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}
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}
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return strings.TrimSpace(sb.String())
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}
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func safeSubstr(s string, start int, end int) string {
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count := len(s)
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start = min(max(start, 0), count)
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end = min(max(end, start), count)
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return s[start:end]
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}
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func min(a int, b int) int {
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if a < b {
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return a
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}
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return b
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}
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func max(a int, b int) int {
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if a > b {
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return a
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}
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return b
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}
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