package docs

import (
	"bytes"
	"encoding/json"
	"flag"
	"os"
	"path/filepath"
	"reflect"
	"regexp"
	"strings"
	"testing"
)

// The drift gate: every doc that declares an endpoint in frontmatter must
// (1) match a real route registration, (2) match its middleware-derived auth
// label, and (3) have request/response examples compatible with the schema
// registry. Docs without frontmatter (overviews, contracts) are out of scope.
//
// Run verbose to see UNVERIFIED markers left by drafting passes:
//
//	go test ./internal/docs/ -run TestDocsMatchRoutes -v

// ---------- route extraction ----------

type extractedRoute struct {
	method     string
	path       string
	middleware []string
}

var (
	groupRe      = regexp.MustCompile(`^(\w+)\s*:=\s*(\S+)\.Group\("([^"]*)"(?:,\s*(.+))?\)`)
	useRe        = regexp.MustCompile(`^(\w+)\.Use\((.+)\)$`)
	echoRouteRe  = regexp.MustCompile(`^(?:e|cfg\.Echo)\.(GET|POST|PUT|PATCH|DELETE)\("([^"]*)"(?:,\s*(.+))?\)`)
	groupRouteRe = regexp.MustCompile(`^(\w+)\.(GET|POST|PUT|PATCH|DELETE)\("([^"]*)"(?:,\s*(.+))?\)`)
)

// extractRoutesFromRouterSource parses internal/router/*.go the way the echo
// router resolves them: group prefixes concatenate, and some files receive
// their group as a function parameter (registerScannerRoutes(protected, ...)).
// This is a test — if it drifts from reality, a doc vs route mismatch shows up
// in live behavior; treat failures here as "the parser needs updating", never
// as license to edit docs to match the parser.
func extractRoutesFromRouterSource(t *testing.T) map[string]extractedRoute {
	t.Helper()
	type group struct {
		prefix     string
		middleware []string
	}
	groups := map[string]group{
		"e":        {},
		"cfg.Echo": {},
	}

	files, err := filepath.Glob("../router/*.go")
	if err != nil || len(files) == 0 {
		t.Fatalf("cannot read router sources: %v", err)
	}

	routes := map[string]extractedRoute{}
	add := func(method, path string, mw []string) {
		routes[method+" "+path] = extractedRoute{method, path, mw}
	}

	for _, file := range files {
		base := filepath.Base(file)
		if strings.HasSuffix(base, "_test.go") {
			continue
		}
		// registerScannerRoutes receives its groups as parameters; seed the
		// names the call site actually passes (router.go: protected=/api jwt,
		// admin=/api jwt+admin).
		if base == "scanner.go" {
			// Middleware values must carry the marker substrings authLabel
			// matches on (AdminMiddleware, createJWTMiddleware) — the seeded
			// "jwt"/"admin" tokens were invisible to it.
			groups["protected"] = group{prefix: "/api", middleware: []string{"jwtMiddleware"}}
			groups["admin"] = group{prefix: "/api", middleware: []string{"jwtMiddleware", "AdminMiddleware"}}
		}
		raw, err := os.ReadFile(file)
		if err != nil {
			t.Fatalf("read %s: %v", file, err)
		}
		for _, line := range strings.Split(string(raw), "\n") {
			s := strings.TrimSpace(line)

			if m := groupRe.FindStringSubmatch(s); m != nil {
				varname, parent, prefix, mwArg := m[1], m[2], m[3], m[4]
				parentInfo := groups[parent]
				g := group{
					prefix:     strings.TrimSuffix(parentInfo.prefix+prefix, "/"),
					middleware: append(append([]string{}, parentInfo.middleware...), splitMW(mwArg)...),
				}
				groups[varname] = g
				continue
			}

			//opds-style middleware: `grp.Use(cfg.DeviceAuthMiddleware.Authenticate)`
			//applies to every route registered on that group afterwards.
			if m := useRe.FindStringSubmatch(s); m != nil {
				if g, ok := groups[m[1]]; ok {
					g.middleware = append(g.middleware, splitMW(m[2])...)
					groups[m[1]] = g
				}
				continue
			}

			if m := echoRouteRe.FindStringSubmatch(s); m != nil {
				add(m[1], m[2], splitMW(m[3]))
				continue
			}

			if m := groupRouteRe.FindStringSubmatch(s); m != nil {
				g, ok := groups[m[1]]
				if !ok {
					continue
				}
				full := strings.TrimSuffix(g.prefix+m[3], "/")
				add(m[2], full, append(append([]string{}, g.middleware...), splitMW(m[4])...))
			}
		}
	}
	return routes
}

func splitMW(s string) []string {
	if strings.TrimSpace(s) == "" {
		return nil
	}
	var out []string
	for _, part := range strings.Split(s, ",") {
		out = append(out, strings.TrimSpace(part))
	}
	return out
}

// authLabel reduces a middleware chain to the frontmatter auth vocabulary.
func authLabel(chain []string) string {
	has := func(needle string) bool {
		for _, c := range chain {
			if strings.Contains(c, needle) {
				return true
			}
		}
		return false
	}
	switch {
	case has("AdminMiddleware"):
		return "jwt+admin"
	case has("DeviceAuthMiddleware"):
		return "device-token"
	case has("createOptionalAuthMiddleware"):
		return "optional-jwt"
	case has("JWTMiddleware"):
		// Wrapper-inlined forms like createJWTMiddleware(cfg) carry uppercase
		// JWT; bare jwtMiddleware carries lowercase. Match both.
		fallthrough
	case has("jwt"):
		return "jwt"
	default:
		return "none"
	}
}

// parseHandlerMiddleware extracts per-route middleware markers from the
// registration's argument list (wrappers like rateLimitMiddleware(handler)).
func parseHandlerMiddleware(rest string) []string {
	if rest == "" {
		return nil
	}
	var mw []string
	if strings.HasPrefix(strings.TrimSpace(rest), "rateLimitMiddleware") {
		mw = append(mw, "rateLimit")
	}
	if strings.Contains(rest, "AdminMiddleware") {
		mw = append(mw, "admin")
	}
	if strings.Contains(rest, "DeviceAuthMiddleware") {
		mw = append(mw, "device-token")
	}
	if strings.Contains(rest, "createJWTMiddleware") {
		mw = append(mw, "jwt")
	}
	return mw
}

// ---------- the gate ----------

// TestBrunoMirrorsDocs keeps the executable-verification layer honest:
// every frontmatter'd endpoint doc must have a generated OpenCollection
// (Bruno) request whose method and URL shape match. Bruno is regenerated
// from the docs; if this test fails, the collection drifted from the
// canonical docs or a new doc was added without regenerating.
//
// Regenerate with:  go test ./internal/docs -run TestBrunoMirrorsDocs -update
var updateBruno = flag.Bool("update", false, "rewrite generated Bruno mirrors from the canonical docs")

func TestBrunoMirrorsDocs(t *testing.T) {
	docsDir := docsRoot
	docs, err := LoadAPIDocs(docsDir)
	if err != nil {
		t.Fatalf("walk %s: %v", docsDir, err)
	}

	if *updateBruno {
		written, deleted, err := updateBrunoMirrors(docs)
		if err != nil {
			t.Fatalf("regenerate bruno mirrors: %v", err)
		}
		if err := updateOpenAPISpec(docs); err != nil {
			t.Fatalf("regenerate openapi spec: %v", err)
		}
		t.Logf("bruno mirrors: %d written, %d deleted", len(written), len(deleted))
		for _, rel := range written {
			t.Logf("  wrote %s", rel)
		}
		for _, rel := range deleted {
			t.Logf("  deleted %s", rel)
		}
		t.Logf("openapi spec written")
	} else if _, err := os.Stat(filepath.Join(docsRoot, "..", "openapi.yaml")); err != nil {
		t.Errorf("docs/developer/openapi.yaml missing — regenerate with: go test ./internal/docs -run TestBrunoMirrorsDocs -update")
	}

	// Collect bruno requests: "METHOD normalized-path" -> relpath.
	bruno := map[string]string{}
	files, _ := filepath.Glob("../../bruno/**/*.yml")
	for _, file := range files {
		rel, _ := filepath.Rel("../../bruno", file)
		parts := strings.Split(rel, string(filepath.Separator))
		if len(parts) > 0 && (parts[0] == "NewDevDBSetup" || parts[0] == "environments") {
			continue
		}
		if strings.Contains(file, "/scenarios/") || strings.Contains(file, "/filters/") || strings.Contains(file, "/search/") {
			continue // hand-authored edge-case suites, not 1:1 mirrors
		}
		raw, err := os.ReadFile(file)
		if err != nil {
			t.Fatalf("read %s: %v", file, err)
		}
		var method, url string
		for _, line := range strings.Split(string(raw), "\n") {
			s := strings.TrimSpace(line)
			if m := regexp.MustCompile(`^method:\s*(\w+)$`).FindStringSubmatch(s); m != nil && method == "" {
				method = strings.ToUpper(m[1])
			}
			if m := regexp.MustCompile(`^url:\s*'?([^']+)`).FindStringSubmatch(s); m != nil && url == "" {
				url = m[1]
			}
		}
		if method == "" || url == "" {
			continue // folder.yml and other metadata
		}
		// {{base_url}}/api/x/{{var}} -> /api/x/{} (params collapse to {})
		path := regexp.MustCompile(`^\{\{(?:base|opds_base)_url\}\}`).ReplaceAllString(url, "")
		path = regexp.MustCompile(`\{\{[^}]+\}\}`).ReplaceAllString(path, "{}")
		bruno[method+" "+path] = rel
	}

	for _, doc := range docs {
		path := regexp.MustCompile(`:[^/{}]+`).ReplaceAllString(doc.Frontmatter.Path, "{}")
		key := doc.Frontmatter.Method + " " + path
		if _, ok := bruno[key]; !ok {
			t.Errorf("%s: no Bruno request mirrors %q — regenerate: go test ./internal/docs -run TestBrunoMirrorsDocs -update", doc.RelPath, key)
		}
	}
}

func TestDocsMatchRoutes(t *testing.T) {
	routes := extractRoutesFromRouterSource(t)

	docsDir := "../../docs/developer/api"
	docs, err := LoadAPIDocs(docsDir)
	if err != nil {
		t.Fatalf("walk %s: %v", docsDir, err)
	}
	if len(docs) == 0 {
		t.Fatal("no frontmatter'd endpoint docs found — the gate is checking nothing")
	}

	for _, doc := range docs {
		key := doc.Frontmatter.Method + " " + doc.Frontmatter.Path

		route, ok := routes[key]
		if !ok {
			t.Errorf("%s: frontmatter declares %q but no such route is registered (wrong path, method, or the route moved)", doc.RelPath, key)
			continue
		}

		if want := authLabel(route.middleware); doc.Frontmatter.Auth != want {
			t.Errorf("%s: frontmatter auth=%q but route middleware resolves to %q", doc.RelPath, doc.Frontmatter.Auth, want)
		}

		for _, marker := range doc.Unverified {
			t.Logf("UNVERIFIED in %s: %s", doc.RelPath, marker)
		}

		schema, registered := Schemas[key]
		if !registered {
			t.Errorf("%s: route %q has no internal/docs schema registry entry — add one in the same change", doc.RelPath, key)
			continue
		}

		validateRequestExample(t, &doc, schema)
		validateResponseExample(t, &doc, schema)
	}
}

func validateRequestExample(t *testing.T, doc *APIDoc, schema Schema) {
	t.Helper()
	if schema.Request == nil {
		if len(doc.ExampleRequest) > 0 {
			t.Errorf("%s: route takes no request body but the doc has an example-request block", doc.RelPath)
		}
		return
	}
	if len(doc.ExampleRequest) == 0 {
		t.Errorf("%s: no example-request block — required for routes with a body", doc.RelPath)
		return
	}

	// AnyJSONObject request: arbitrary keys (config maps). Shape-check only.
	if _, ok := schema.Request.(AnyJSONObject); ok {
		var m map[string]json.RawMessage
		if err := json.Unmarshal(doc.ExampleRequest, &m); err != nil {
			t.Errorf("%s: example-request must be a JSON object", doc.RelPath)
		}
		return
	}

	// Typo guard: field names must exist on the bind struct.
	dec := json.NewDecoder(bytes.NewReader(doc.ExampleRequest))
	dec.DisallowUnknownFields()
	v := reflect.New(reflect.TypeOf(schema.Request)).Interface()
	if err := dec.Decode(v); err != nil {
		t.Errorf("%s: example-request is not compatible with %T: %v", doc.RelPath, schema.Request, err)
		return
	}

	// Staleness guard: required fields must be present in the example.
	rt := reflect.TypeOf(schema.Request)
	for rt != nil && rt.Kind() == reflect.Ptr {
		rt = rt.Elem()
	}
	if rt != nil && rt.Kind() == reflect.Struct {
		for _, field := range requiredJSONFields(rt) {
			if !jsonHasKey(doc.ExampleRequest, field) {
				t.Errorf("%s: example-request missing required field %q", doc.RelPath, field)
			}
		}
	}
}

func validateResponseExample(t *testing.T, doc *APIDoc, schema Schema) {
	t.Helper()
	if schema.Response == nil {
		if doc.HasExampleResponse {
			t.Errorf("%s: route returns no JSON body but the doc has an example-response block", doc.RelPath)
		}
		return
	}
	if !doc.HasExampleResponse {
		t.Errorf("%s: no example-response block — required for JSON routes", doc.RelPath)
		return
	}

	// AnyJSONObject: response is an object with arbitrary/dynamic keys
	// (e.g. map[string]string config). Only shape-check, never key-check.
	if _, ok := schema.Response.(AnyJSONObject); ok {
		var m map[string]json.RawMessage
		if err := json.Unmarshal(doc.ExampleResponse, &m); err != nil {
			t.Errorf("%s: example-response must be a JSON object", doc.RelPath)
		}
		return
	}

	want, isSlice := responseTopLevelKeys(t, schema.Response)

	var got map[string]bool
	if isSlice {
		// Array responses: compare the first sample element's keys.
		var arr []json.RawMessage
		if err := json.Unmarshal(doc.ExampleResponse, &arr); err != nil {
			t.Errorf("%s: example-response must be a JSON array for this route (handler returns a slice)", doc.RelPath)
			return
		}
		if len(arr) == 0 {
			t.Errorf("%s: example-response array needs at least one sample element to check keys", doc.RelPath)
			return
		}
		got = topLevelKeys(arr[0])
	} else {
		got = topLevelKeys(doc.ExampleResponse)
	}

	for _, k := range sortedKeys(want) {
		if !got[k] {
			t.Errorf("%s: example-response missing key %q (the handler emits it)", doc.RelPath, k)
		}
	}
	for _, k := range sortedKeys(got) {
		if !want[k] {
			t.Errorf("%s: example-response has key %q but the handler does not emit it", doc.RelPath, k)
		}
	}
}

// requiredJSONFields lists json field names of struct type whose validate tag
// marks them required. Callers must pass a struct kind.
func requiredJSONFields(rt reflect.Type) []string {
	if rt.Kind() == reflect.Ptr {
		rt = rt.Elem()
	}
	var out []string
	for i := 0; i < rt.NumField(); i++ {
		f := rt.Field(i)
		jsonTag := strings.Split(f.Tag.Get("json"), ",")[0]
		if jsonTag == "" || jsonTag == "-" {
			continue
		}
		for _, rule := range strings.Split(f.Tag.Get("validate"), ",") {
			if strings.TrimSpace(rule) == "required" {
				out = append(out, jsonTag)
				break
			}
		}
	}
	return out
}

func jsonHasKey(data []byte, key string) bool {
	var m map[string]json.RawMessage
	if err := json.Unmarshal(data, &m); err != nil {
		return false
	}
	_, ok := m[key]
	return ok
}

func topLevelKeys(data []byte) map[string]bool {
	var m map[string]json.RawMessage
	if err := json.Unmarshal(data, &m); err != nil {
		return nil
	}
	out := make(map[string]bool, len(m))
	for k := range m {
		out[k] = true
	}
	return out
}

// responseTopLevelKeys derives the expected top-level key set from the
// registered Response: marshal a struct (or its element for slices), or use a
// RawMessage pin verbatim. The second return reports that the handler emits a
// JSON ARRAY (slice response) — the doc's example must then be an array too.
func responseTopLevelKeys(t *testing.T, resp any) (map[string]bool, bool) {
	t.Helper()
	if raw, ok := resp.(json.RawMessage); ok {
		trimmed := bytes.TrimLeft(raw, " \t\r\n")
		return topLevelKeys(raw), len(trimmed) > 0 && trimmed[0] == '['
	}
	rt := reflect.TypeOf(resp)
	if rt == nil {
		return nil, false
	}
	isSlice := false
	if rt.Kind() == reflect.Slice {
		if rt.Elem().Kind() == reflect.Uint8 {
			return topLevelKeys(reflect.ValueOf(resp).Bytes()), false // []byte payloads
		}
		rt = rt.Elem()
		isSlice = true
	}
	if rt.Kind() == reflect.Ptr {
		rt = rt.Elem()
	}
	if rt.Kind() != reflect.Struct {
		t.Fatalf("schema response %T: unsupported kind %s (use a struct, slice of struct, or json.RawMessage)", resp, rt.Kind())
	}
	b, err := json.Marshal(reflect.New(rt).Interface())
	if err != nil {
		t.Fatalf("marshal schema response %T: %v", resp, err)
	}
	return topLevelKeys(b), isSlice
}

func sortedKeys(m map[string]bool) []string {
	out := make([]string, 0, len(m))
	for k := range m {
		out = append(out, k)
	}
	// deterministic order for stable failure messages
	for i := 1; i < len(out); i++ {
		for j := i; j > 0 && out[j] < out[j-1]; j-- {
			out[j], out[j-1] = out[j-1], out[j]
		}
	}
	return out
}

// Sanity: the extraction itself must find the pilot routes, otherwise the
// gate would pass vacuously if the parser ever broke.
func TestRouteExtractionFindsPilots(t *testing.T) {
	routes := extractRoutesFromRouterSource(t)
	for _, key := range []string{
		"POST /api/collections",
		"GET /api/collections",
		"GET /api/collections/:id",
		"PUT /api/collections/:id",
		"DELETE /api/collections/:id",
		"GET /api/admin/hash-conflicts",
		"POST /api/admin/hash-conflicts/:id/resolve",
		"POST /api/sync/kobo/:token/markup",
		"POST /api/auth/login",
	} {
		if _, ok := routes[key]; !ok {
			t.Errorf("route extraction missing %q (parser drift — fix extractRoutesFromRouterSource, do not edit docs to match)", key)
		}
	}
	if label := authLabel(routes["GET /api/admin/hash-conflicts"].middleware); label != "jwt+admin" {
		t.Errorf("hash-conflicts auth label = %q, want jwt+admin", label)
	}
	if label := authLabel(routes["POST /api/sync/kobo/:token/markup"].middleware); label != "device-token" {
		t.Errorf("kobo markup auth label = %q, want device-token", label)
	}
	if label := authLabel(routes["POST /api/auth/login"].middleware); label != "none" {
		t.Errorf("login auth label = %q, want none (public, rate-limited)", label)
	}
}