package o11y_test

import (
	"net/http"
	"net/http/httptest"
	"os"
	"sort"
	"strings"
	"testing"

	"github.com/hanzoai/o11y"
	"github.com/zap-proto/zip"
)

// THE CENSUS. This file is the arithmetic that the wildcard used to hide.
//
// While Mount ended in app.All("/v1/o11y/*", …) there was no way to tell a
// converted route from an unconverted one from a MISSING one: the catch-all
// answered all three the same. That is exactly how 83 typed ops shipped in
// files nothing called — the package built, the suite passed, and every one of
// those routes still fell through the wildcard. These tests are the replacement
// for that catch-all's silence.

// registered is every non-HEAD, non-OPTIONS route the mount actually installed.
func registered(t *testing.T, app *zip.App) map[string]bool {
	t.Helper()
	got := map[string]bool{}
	for _, r := range app.Fiber().GetRoutes(true) {
		if r.Method == http.MethodHead || r.Method == http.MethodOptions {
			continue
		}
		got[r.Method+" "+r.Path] = true
	}
	return got
}

// assertRoutes proves a slice registered EXACTLY its own routes under prefix —
// no more, no fewer, at the same methods. Each slice counts only its own routes,
// so a slice that stops being mounted fails here rather than being quietly
// answered by something else.
func assertRoutes(t *testing.T, want map[string]bool, prefix string) {
	t.Helper()
	got := map[string]bool{}
	for route := range registered(t, mounted(t)) {
		_, path, _ := strings.Cut(route, " ")
		if path == prefix || strings.HasPrefix(path, prefix+"/") {
			got[route] = true
		}
	}
	for route := range want {
		if !got[route] {
			t.Errorf("%s is not registered", route)
		}
	}
	for route := range got {
		if !want[route] {
			t.Errorf("%s is registered but not in the census", route)
		}
	}
}

// THE WHOLE SURFACE, counted. 324 is the number of method+path pairs the o11y
// runtime registers on its gorilla/mux tree (pkg/query-service/app/routes_*.go
// and pkg/apiserver/o11yapiserver/*.go). Mount registers the same 324 — 318 as
// typed ops that carry a named In, a named Out and their prose into the
// document, 3 as named escape hatches, 3 as native service probes.
//
// If this number moves, one of two things happened and both need a human: a
// route was added to the runtime and not named here (it would 404 in the
// composed binary), or a route was named here that the runtime does not serve
// (it would 404 at the runtime). Neither is visible without the count.
func TestEveryRouteIsNamedAndCounted(t *testing.T) {
	app := mounted(t)
	all := registered(t, app)

	const (
		wantTyped   = 318 // typed ops: in the OpenAPI document and the MCP tool list
		wantHatches = 3   // mount.go mountHatches, each with its reason
		wantProbes  = 3   // health.go livez/healthz/readyz, native with fall-through
	)
	if len(all) != wantTyped+wantHatches+wantProbes {
		t.Fatalf("mount registered %d routes, want %d", len(all), wantTyped+wantHatches+wantProbes)
	}

	// The typed ops are exactly the operations zip published. Counting them off
	// the document rather than off the router is what makes this a payoff
	// measurement and not a tautology: an op that reaches the router but not the
	// document is the defect this whole conversion exists to remove.
	spec := app.OpenAPISpec()
	if got := len(app.MCPTools()); got != wantTyped {
		t.Fatalf("MCP tools = %d, want %d", got, wantTyped)
	}
	paths, ok := spec["paths"].(map[string]map[string]any)
	if !ok {
		t.Fatalf("OpenAPI paths has type %T", spec["paths"])
	}
	ops := 0
	for path, item := range paths {
		if !strings.HasPrefix(path, "/v1/o11y") && !strings.HasPrefix(path, "/v1/o11y/sentinel") {
			t.Errorf("OpenAPI published %s, which is not o11y's surface", path)
		}
		for method := range item {
			switch method {
			case "get", "post", "put", "patch", "delete":
				ops++
			}
		}
	}
	if ops != wantTyped {
		t.Fatalf("OpenAPI operations = %d, want %d", ops, wantTyped)
	}
}

// The table, address by address. The count above says how many routes there
// are; testdata/routes.txt says which, so a route that moves, disappears or
// changes its spelling reads as a diff instead of as a count that still adds up.
func TestRouteTableIsTheCensus(t *testing.T) {
	census, err := os.ReadFile("testdata/routes.txt")
	if err != nil {
		t.Fatalf("read the census: %v", err)
	}
	var got []string
	for route := range registered(t, mounted(t)) {
		got = append(got, route)
	}
	sort.Strings(got)
	if moved := drift(strings.Split(strings.TrimSpace(string(census)), "\n"), got); moved != "" {
		t.Errorf("the route table is not the one in testdata/routes.txt:\n%s", moved)
	}
}

// drift names what the census holds and the mount does not, and the reverse.
func drift(want, got []string) string {
	held, have := map[string]bool{}, map[string]bool{}
	for _, w := range want {
		held[w] = true
	}
	for _, g := range got {
		have[g] = true
	}
	var out []string
	for _, w := range want {
		if !have[w] {
			out = append(out, "  gone: "+w)
		}
	}
	for _, g := range got {
		if !held[g] {
			out = append(out, "  new:  "+g)
		}
	}
	return strings.Join(out, "\n")
}

// No route may end in a wildcard. This is the invariant the whole change buys:
// a NEW un-typed route is a 404 someone has to come and justify, not a silent
// fall-through into the runtime.
func TestNoCatchAllRemains(t *testing.T) {
	for route := range registered(t, mounted(t)) {
		if strings.HasSuffix(route, "*") || strings.HasSuffix(route, "/+") {
			t.Errorf("%s is a catch-all", route)
		}
	}
}

// A path under /v1/o11y that nothing named is a 404 — proof the catch-all is
// gone. Under the wildcard this same request reached the runtime, which is why
// an unmounted slice could go unnoticed.
func TestUnnamedPathIsNotServed(t *testing.T) {
	app := mounted(t)
	served := false
	setRuntime(t, func(w http.ResponseWriter, r *http.Request) {
		served = true
		w.WriteHeader(http.StatusOK)
	})

	status, _ := call(t, app, member(http.MethodGet, "/v1/o11y/no-such-thing", nil))
	if status != http.StatusNotFound {
		t.Fatalf("status=%d want 404", status)
	}
	if served {
		t.Fatal("an unnamed path still reached the runtime")
	}
}

// setRuntime installs a stand-in runtime for the duration of the test.
func setRuntime(t *testing.T, fn http.HandlerFunc) {
	t.Helper()
	o11y.SetRuntime(o11y.Whole(fn))
	t.Cleanup(func() { o11y.SetRuntime(nil) })
}

// THE THREE. Each hatch is registered at its exact method and path, and each
// delegates with the path UNTOUCHED — a rewrite at this seam can only ever move
// a request off its own route, and a mangler is invisible to the compiler, so
// this is the only thing that catches one coming back.
func TestHatchesDelegateVerbatim(t *testing.T) {
	hatches := []struct{ method, path string }{
		{http.MethodGet, "/v1/o11y/logs/livetail"},
		{http.MethodGet, "/v1/o11y/query_progress"},
		{http.MethodPost, "/v1/o11y/export_raw_data"},
	}
	if len(hatches) != 3 {
		t.Fatalf("the census itself is wrong: %d", len(hatches))
	}

	app := mounted(t)
	var saw string
	setRuntime(t, func(w http.ResponseWriter, r *http.Request) {
		saw = r.URL.Path
		w.WriteHeader(http.StatusOK)
	})

	for _, h := range hatches {
		t.Run(h.method+" "+h.path, func(t *testing.T) {
			saw = ""
			status, body := call(t, app, member(h.method, h.path, strings.NewReader("{}")))
			if status != http.StatusOK {
				t.Fatalf("status=%d body=%s", status, body)
			}
			if saw != h.path {
				t.Fatalf("runtime received %q, want %q verbatim", saw, h.path)
			}
		})
	}
}

// A hatch answers 503 rather than 404 while no runtime is registered — the same
// honest "not initialized yet" the wildcard gave, kept now that each hatch is
// its own route.
func TestHatchWithoutRuntimeIs503(t *testing.T) {
	app := mounted(t)
	o11y.SetRuntime(nil)
	resp, err := app.Test(httptest.NewRequest(http.MethodGet, "/v1/o11y/logs/livetail", nil))
	if err != nil {
		t.Fatalf("Test: %v", err)
	}
	if resp.StatusCode != http.StatusServiceUnavailable {
		t.Fatalf("status=%d want 503", resp.StatusCode)
	}
}

// TestEveryOperationDeclaresItsOwnId holds what made this package's op target
// unnecessary.
//
// An op with no declared id takes zip's shape-derived one, and that one is
// qualified by the prefix of the occurrence it answers under — so registering
// through a group used to publish every undeclared op as "v1.o11y.<derived>",
// a rename that once cost 353 ids. A struct answering with a fixed prefix was
// the way around it. Once every op states its id, a declared id survives
// composition verbatim and the group is just a group; the test that measured
// that gap reached zero and said so, which is why the struct is gone.
//
// This is the same property from the other side: the number that has to stay at
// zero is the UNDECLARED one.
func TestEveryOperationDeclaresItsOwnId(t *testing.T) {
	app := mounted(t)
	if err := app.Build(); err != nil {
		t.Fatalf("Build: %v", err)
	}

	var undeclared []string
	for _, op := range app.Registry() {
		if op.OperationID == "" {
			undeclared = append(undeclared, op.Method+" "+op.Path)
		}
	}
	if len(undeclared) != 0 {
		t.Errorf("%d of %d ops declare no id, so composition would rename them: %v",
			len(undeclared), len(app.Registry()), undeclared)
	}
	if len(app.Registry()) != 318 {
		t.Errorf("registry holds %d ops, want the 318 of TestEveryRouteIsNamedAndCounted", len(app.Registry()))
	}

	// The property itself, on the real mount: nothing this service publishes
	// carries the occurrence qualification.
	for _, tool := range app.MCPTools() {
		name, _ := tool["name"].(string)
		if strings.HasPrefix(name, "v1.") {
			t.Errorf("published name %q is prefix-qualified", name)
		}
	}
}