75 lines
1.8 KiB
Go
75 lines
1.8 KiB
Go
package migrator
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import (
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"errors"
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"io"
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"io/ioutil"
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"strings"
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)
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// URLMapper implements Mapper interface
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type URLMapper struct {
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rules map[string]string
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}
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// NewURLMapper reads rules from given reader and returns initialized URLMapper
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// if given rules are valid.
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func NewURLMapper(reader io.Reader) (Mapper, error) {
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u := &URLMapper{}
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if err := u.loadRules(reader); err != nil {
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return u, err
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}
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return u, nil
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}
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// loadRules loads url-mapping rules from reader to mapper.
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// Rules must be a text consists of rows separated by \n.
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// Each row holds from-url and to-url separated by space.
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// If urls end with asterisk (*) it means try to match by prefix.
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// Example:
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// https://www.myblog.com/blog/1/ https://myblog.com/blog/1/
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// https://www.myblog.com/* https://myblog.com/*
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func (u *URLMapper) loadRules(reader io.Reader) error {
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data, err := ioutil.ReadAll(reader)
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if err != nil {
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return err
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}
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rulesText := strings.TrimSpace(string(data))
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u.rules = make(map[string]string)
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for _, row := range strings.Split(rulesText, "\n") {
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row = strings.TrimSpace(row)
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urls := strings.Split(row, " ")
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if len(urls) != 2 {
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return errors.New("bad row " + row)
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}
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from, to := strings.TrimSpace(urls[0]), strings.TrimSpace(urls[1])
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u.rules[from] = to
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}
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return nil
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}
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// URL maps given url to another url according loaded url-rules.
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// If not matched returns given url.
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func (u *URLMapper) URL(url string) string {
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if newURL, ok := u.rules[url]; ok {
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return newURL
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}
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// try to match by prefix
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for oldURL, newURL := range u.rules {
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if !strings.HasSuffix(oldURL, "*") {
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continue
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}
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oldURL = strings.TrimSuffix(oldURL, "*")
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newURL = strings.TrimSuffix(newURL, "*")
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if strings.HasPrefix(url, oldURL) {
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return newURL + strings.TrimPrefix(url, oldURL)
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}
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}
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// search failed, return given url
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return url
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}
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