| 1 | package agent |
| 2 | |
| 3 | import ( |
| 4 | "context" |
| 5 | "encoding/json" |
| 6 | "io" |
| 7 | "os" |
| 8 | |
| 9 | "reasonix/internal/historywork" |
| 10 | ) |
| 11 | |
| 12 | // Native writers put identifying fields first. Legacy writers may reorder JSON |
| 13 | // fields, so a bounded-prefix miss falls back to a cancellable token walk, not |
| 14 | // a Decode of the entire event (which may contain all session messages). |
| 15 | func probeDisplayEventHeader(ctx context.Context, file *os.File) (int, string, bool, error) { |
| 16 | schema, kind, known := probeSessionEventHeader(&historywork.Reader{Context: ctx, Source: file}) |
| 17 | if known || ctx.Err() != nil { |
| 18 | return schema, kind, known, ctx.Err() |
| 19 | } |
| 20 | if _, err := file.Seek(0, io.SeekStart); err != nil { |
| 21 | return 0, "", false, err |
| 22 | } |
| 23 | decoder := json.NewDecoder(&historywork.Reader{Context: ctx, Source: file}) |
| 24 | token, err := decoder.Token() |
| 25 | if err != nil || token != json.Delim('{') { |
| 26 | return 0, "", false, ctx.Err() |
| 27 | } |
| 28 | haveSchema, haveType := false, false |
| 29 | for decoder.More() { |
| 30 | name, err := decoder.Token() |
| 31 | if err != nil { |
| 32 | return 0, "", false, ctx.Err() |
| 33 | } |
| 34 | switch name { |
| 35 | case "schema_version": |
| 36 | err = decoder.Decode(&schema) |
| 37 | haveSchema = err == nil |
| 38 | case "type": |
| 39 | err = decoder.Decode(&kind) |
| 40 | haveType = err == nil |
| 41 | default: |
| 42 | err = skipDisplayJSONValue(ctx, decoder) |
| 43 | } |
| 44 | if err != nil { |
| 45 | return 0, "", false, ctx.Err() |
| 46 | } |
| 47 | if haveSchema && haveType { |
| 48 | return schema, kind, true, nil |
| 49 | } |
| 50 | } |
| 51 | return 0, "", false, ctx.Err() |
| 52 | } |
| 53 |