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| 1 | +package cidenc |
| 2 | + |
| 3 | +import ( |
| 4 | + cid "gx/ipfs/QmPSQnBKM9g7BaUcZCvswUJVscQ1ipjmwxN5PXCjkp9EQ7/go-cid" |
| 5 | + path "gx/ipfs/QmX7uSbkNz76yNwBhuwYwRbhihLnJqM73VTCjS3UMJud9A/go-path" |
| 6 | + mbase "gx/ipfs/QmekxXDhCxCJRNuzmHreuaT3BsuJcsjcXWNrtV9C8DRHtd/go-multibase" |
| 7 | +) |
| 8 | + |
| 9 | +// Encoder is a type used to encode or recode Cid as the user |
| 10 | +// specifies |
| 11 | +type Interface interface { |
| 12 | + Encode(c cid.Cid) string |
| 13 | + Recode(v string) (string, error) |
| 14 | +} |
| 15 | + |
| 16 | +// Basic is a basic Encoder that will encode Cid's using |
| 17 | +// a specifed base, optionally upgrading a Cid if is Version 0 |
| 18 | +type Encoder struct { |
| 19 | + Base mbase.Encoder |
| 20 | + Upgrade bool |
| 21 | +} |
| 22 | + |
| 23 | +var Default = Encoder{ |
| 24 | + Base: mbase.MustNewEncoder(mbase.Base58BTC), |
| 25 | + Upgrade: false, |
| 26 | +} |
| 27 | + |
| 28 | +func (enc Encoder) Encode(c cid.Cid) string { |
| 29 | + if enc.Upgrade && c.Version() == 0 { |
| 30 | + c = cid.NewCidV1(c.Type(), c.Hash()) |
| 31 | + } |
| 32 | + return c.Encode(enc.Base) |
| 33 | +} |
| 34 | + |
| 35 | +func (enc Encoder) Recode(v string) (string, error) { |
| 36 | + skip, err := enc.NoopRecode(v) |
| 37 | + if skip || err != nil { |
| 38 | + return v, err |
| 39 | + } |
| 40 | + |
| 41 | + c, err := cid.Decode(v) |
| 42 | + if err != nil { |
| 43 | + return v, err |
| 44 | + } |
| 45 | + |
| 46 | + return enc.Encode(c), nil |
| 47 | +} |
| 48 | + |
| 49 | +func (enc Encoder) NoopRecode(v string) (bool, error) { |
| 50 | + if len(v) < 2 { |
| 51 | + return false, cid.ErrCidTooShort |
| 52 | + } |
| 53 | + ver := cidVer(v) |
| 54 | + skip := ver == 0 && !enc.Upgrade || ver == 1 && v[0] == byte(enc.Base.Encoding()) |
| 55 | + return skip, nil |
| 56 | +} |
| 57 | + |
| 58 | +func cidVer(v string) int { |
| 59 | + if len(v) == 46 && v[:2] == "Qm" { |
| 60 | + return 0 |
| 61 | + } else { |
| 62 | + return 1 |
| 63 | + } |
| 64 | +} |
| 65 | + |
| 66 | +// On error an unmodified encoder will be returned so it is safe to |
| 67 | +// ignore the error |
| 68 | +func (enc Encoder) FromPath(p string) (Encoder, error) { |
| 69 | + v := extractCidString(p) |
| 70 | + if cidVer(v) == 0 { |
| 71 | + return Encoder{enc.Base, false}, nil |
| 72 | + } |
| 73 | + e, err := mbase.NewEncoder(mbase.Encoding(v[0])) |
| 74 | + if err != nil { |
| 75 | + return enc, err |
| 76 | + } |
| 77 | + return Encoder{e, true}, nil |
| 78 | +} |
| 79 | + |
| 80 | +func extractCidString(p string) string { |
| 81 | + segs := path.FromString(p).Segments() |
| 82 | + v := segs[0] |
| 83 | + if v == "ipfs" && len(segs) > 0 { |
| 84 | + v = segs[1] |
| 85 | + } |
| 86 | + return v |
| 87 | +} |
| 88 | + |
| 89 | +type WithOverride struct { |
| 90 | + base Encoder |
| 91 | + override map[cid.Cid]string |
| 92 | +} |
| 93 | + |
| 94 | +func (enc Encoder) WithOverride(cids ...string) Interface { |
| 95 | + override := map[cid.Cid]string{} |
| 96 | + for _, p := range cids { |
| 97 | + v := p |
| 98 | + skip, err := enc.NoopRecode(v) |
| 99 | + if skip || err != nil { |
| 100 | + continue |
| 101 | + } |
| 102 | + c, err := cid.Decode(v) |
| 103 | + if err != nil { |
| 104 | + continue |
| 105 | + } |
| 106 | + println(v) |
| 107 | + override[c] = v |
| 108 | + } |
| 109 | + if len(override) == 0 { |
| 110 | + return enc |
| 111 | + } |
| 112 | + return WithOverride{enc, override} |
| 113 | +} |
| 114 | + |
| 115 | +func (enc WithOverride) Encode(c cid.Cid) string { |
| 116 | + v, ok := enc.override[c] |
| 117 | + if ok { |
| 118 | + return v |
| 119 | + } |
| 120 | + return enc.base.Encode(c) |
| 121 | +} |
| 122 | + |
| 123 | +func (enc WithOverride) Recode(v string) (string, error) { |
| 124 | + c, err := cid.Decode(v) |
| 125 | + if err != nil { |
| 126 | + return v, err |
| 127 | + } |
| 128 | + |
| 129 | + return enc.Encode(c), nil |
| 130 | +} |
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