Justin Visser
e9f36f509e
internal/api stays a translation layer: decode (with
DisallowUnknownFields so typos 400 instead of silently defaulting),
run the engine, encode; all validation stays in the engine. Routes use
Go 1.22 mux patterns ('POST /api/comparison'), so wrong methods get
405 from the stdlib for free. httptest runs handlers fully in memory;
the API test re-pins the 99/70/7 golden values end to end.
ComparisonResponse is added to tygo.yaml with a type mapping so the
generated web/src/types/api.ts reuses the engine's TS types.
cmd/spreadlab now serves on -addr (default localhost:8080); -table
keeps the CLI comparison as a sanity check.
80 lines
2.6 KiB
Go
80 lines
2.6 KiB
Go
// Package api exposes the engine over HTTP as a small JSON API. It stays
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// thin on purpose: decode, run the engine, encode. All validation lives in
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// the engine; the API only translates errors into status codes.
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package api
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import (
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"encoding/json"
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"fmt"
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"net/http"
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"github.com/JustinZeus/spreadlab/internal/engine"
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)
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// ComparisonResponse bundles what the dashboard needs to render one
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// comparison: the config that was run, echoed back so frontend state stays
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// honest, and one result per strategy.
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type ComparisonResponse struct {
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Config engine.Config `json:"config"`
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Results []engine.Result `json:"results"`
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}
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// errorResponse is the JSON shape of every non-2xx body.
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type errorResponse struct {
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Error string `json:"error"`
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}
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// NewServer returns the API as an http.Handler. Routes use the Go 1.22+
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// pattern syntax, method and path in one string; the stdlib answers 405
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// for wrong methods on a known path by itself.
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func NewServer() http.Handler {
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mux := http.NewServeMux()
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mux.HandleFunc("GET /api/config/default", handleDefaultConfig)
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mux.HandleFunc("POST /api/comparison", handleComparison)
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return mux
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}
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func handleDefaultConfig(w http.ResponseWriter, _ *http.Request) {
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writeJSON(w, http.StatusOK, engine.DefaultConfig())
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}
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func handleComparison(w http.ResponseWriter, r *http.Request) {
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decoder := json.NewDecoder(r.Body)
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decoder.DisallowUnknownFields() // a typo in a field name fails loudly
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var config engine.Config
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if err := decoder.Decode(&config); err != nil {
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writeError(w, http.StatusBadRequest, fmt.Errorf("invalid config: %w", err))
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return
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}
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strategies := engine.AllStrategies()
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results := make([]engine.Result, 0, len(strategies))
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for _, strategy := range strategies {
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result, err := engine.RunScenario(config, strategy)
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if err != nil {
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// The engine only errors on bad parameter values, which is
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// the client's mistake, not the server's.
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writeError(w, http.StatusBadRequest, err)
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return
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}
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results = append(results, result)
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}
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writeJSON(w, http.StatusOK, ComparisonResponse{Config: config, Results: results})
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}
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// writeJSON marshals first and writes after, so an encoding failure can
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// still become a clean 500 instead of a half-written body.
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func writeJSON(w http.ResponseWriter, status int, payload any) {
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body, err := json.Marshal(payload)
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if err != nil {
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http.Error(w, "encoding response failed", http.StatusInternalServerError)
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return
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}
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w.Header().Set("Content-Type", "application/json")
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w.WriteHeader(status)
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_, _ = w.Write(body) // a failed write means the client went away
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}
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func writeError(w http.ResponseWriter, status int, err error) {
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writeJSON(w, status, errorResponse{Error: err.Error()})
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}
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