package api_test

import (
	"context"
	"database/sql"
	"encoding/base64"
	"encoding/json"
	"io"
	"net/http"
	"net/http/httptest"
	"os"
	"path/filepath"
	"strings"
	"testing"

	"halcyon/api"
	"halcyon/config"
	"halcyon/store"
	"halcyon/web"
)

// newSite starts the API with the web front end mounted, as cmd/server does.
func newSite(t *testing.T, manualPDF string, opts ...api.Option) (*httptest.Server, config.Config) {
	srv, cfg, _ := newSiteStore(t, manualPDF, opts...)
	return srv, cfg
}

// newSiteStore is newSite, also returning the database so tests can run a simulated day.
func newSiteStore(t *testing.T, manualPDF string, opts ...api.Option) (*httptest.Server, config.Config, *store.Store) {
	t.Helper()
	cfg := config.Default()
	dsn := "sqlite:" + filepath.Join(t.TempDir(), "t.db")
	if pg := os.Getenv("HALCYON_TEST_PG"); pg != "" { // run against PostgreSQL, wiping its public schema first
		db, err := sql.Open("pgx", pg)
		if err != nil {
			t.Fatal(err)
		}
		if _, err := db.Exec("DROP SCHEMA public CASCADE; CREATE SCHEMA public"); err != nil {
			t.Fatal(err)
		}
		db.Close()
		dsn = pg
	}
	st, err := store.Open(dsn)
	if err != nil {
		t.Fatal(err)
	}
	t.Cleanup(func() { st.Close() })
	if err := st.Migrate(context.Background()); err != nil {
		t.Fatal(err)
	}
	mux := api.New(st, cfg, opts...)
	mux.Handle("/", web.Handler(manualPDF))
	srv := httptest.NewServer(mux)
	t.Cleanup(srv.Close)
	return srv, cfg, st
}

func get(t *testing.T, url string) (*http.Response, string) {
	t.Helper()
	resp, err := http.Get(url)
	if err != nil {
		t.Fatal(err)
	}
	defer resp.Body.Close()
	b, _ := io.ReadAll(resp.Body)
	return resp, string(b)
}

func TestInfoAndAssemble(t *testing.T) {
	srv, cfg := newSite(t, "")

	_, body := get(t, srv.URL+"/info")
	var info struct {
		ProgramBytes int      `json:"program_bytes"`
		CommBytes    int      `json:"comm_bytes"`
		Ores         []string `json:"ores"`
	}
	if err := json.Unmarshal([]byte(body), &info); err != nil {
		t.Fatal(err)
	}
	if info.ProgramBytes != cfg.ProgramBytes || info.CommBytes != cfg.CommBytes || len(info.Ores) != 4 {
		t.Fatalf("info = %+v", info)
	}

	post := func(src string) (int, map[string]any) {
		resp, err := http.Post(srv.URL+"/assemble", "text/plain", strings.NewReader(src))
		if err != nil {
			t.Fatal(err)
		}
		defer resp.Body.Close()
		var m map[string]any
		json.NewDecoder(resp.Body).Decode(&m)
		return resp.StatusCode, m
	}
	code, m := post("ldi r1, 5\nhalt")
	if code != 200 || m["size"].(float64) != 8 || m["fits"] != true {
		t.Fatalf("assemble ok case: %d %v", code, m)
	}
	if raw, _ := base64.StdEncoding.DecodeString(m["program"].(string)); len(raw) != 8 {
		t.Fatalf("program bytes = %d", len(raw))
	}
	code, m = post("ldi r1, 5\nbogus r1")
	if code != 400 || !strings.Contains(m["error"].(string), "line 2") {
		t.Fatalf("assemble error case: %d %v", code, m)
	}
	// Too big for the belt: assembles, but reports that it does not fit.
	code, m = post(strings.Repeat("nop\n", cfg.ProgramBytes/4+1))
	if code != 200 || m["fits"] != false {
		t.Fatalf("oversize case: %d %v", code, m)
	}
}

func TestWebAssets(t *testing.T) {
	srv, _ := newSite(t, "")
	for path, want := range map[string]string{
		"/":                    "<title>",
		"/manual.md":           "Programmer's Reference Manual",
		"/examples/echo.s":     "ECHO",
		"/examples/index.json": `"pursue"`,
	} {
		resp, body := get(t, srv.URL+path)
		if resp.StatusCode != 200 || !strings.Contains(body, want) {
			t.Errorf("%s: status %d, missing %q", path, resp.StatusCode, want)
		}
	}
	resp, _ := get(t, srv.URL+"/")
	if !strings.Contains(resp.Header.Get("Content-Security-Policy"), "default-src 'self'") {
		t.Error("missing CSP header")
	}
	// The PDF is rendered separately; until it exists /manual.pdf explains how.
	presp, pbody := get(t, srv.URL+"/manual.pdf")
	if presp.StatusCode != 404 || !strings.Contains(pbody, "render-manual.sh") {
		t.Errorf("/manual.pdf before any render: status %d: %s", presp.StatusCode, pbody)
	}
	// The API still wins over the catch-all.
	if resp, _ := get(t, srv.URL+"/market"); !strings.HasPrefix(resp.Header.Get("Content-Type"), "application/json") {
		t.Errorf("/market served as %q", resp.Header.Get("Content-Type"))
	}
}

func TestManualPDFServedFromFileAndPickedUpLive(t *testing.T) {
	path := filepath.Join(t.TempDir(), "manual.pdf")
	srv, _ := newSite(t, path)

	if resp, _ := get(t, srv.URL+"/manual.pdf"); resp.StatusCode != 404 {
		t.Fatalf("before the file exists: %d", resp.StatusCode)
	}
	write := func(content string) {
		// Like the renderer: write beside the target, then rename into place.
		if err := os.WriteFile(path+".tmp", []byte(content), 0o644); err != nil {
			t.Fatal(err)
		}
		if err := os.Rename(path+".tmp", path); err != nil {
			t.Fatal(err)
		}
	}
	write("%PDF-1.7 first render")
	resp, body := get(t, srv.URL+"/manual.pdf")
	if resp.StatusCode != 200 || body != "%PDF-1.7 first render" || resp.Header.Get("Content-Type") != "application/pdf" {
		t.Fatalf("first render: %d %q %q", resp.StatusCode, body, resp.Header.Get("Content-Type"))
	}
	if resp.Header.Get("Cache-Control") != "no-cache" || resp.Header.Get("Content-Security-Policy") != "" {
		t.Errorf("headers: cache=%q csp=%q", resp.Header.Get("Cache-Control"), resp.Header.Get("Content-Security-Policy"))
	}

	// A re-render is served immediately, with no restart.
	write("%PDF-1.7 second render, longer")
	if _, body := get(t, srv.URL+"/manual.pdf"); body != "%PDF-1.7 second render, longer" {
		t.Fatalf("new render not picked up: %q", body)
	}

	// Range requests work (PDF viewers rely on them).
	req, _ := http.NewRequest("GET", srv.URL+"/manual.pdf", nil)
	req.Header.Set("Range", "bytes=0-4")
	rr, err := http.DefaultClient.Do(req)
	if err != nil {
		t.Fatal(err)
	}
	defer rr.Body.Close()
	if part, _ := io.ReadAll(rr.Body); rr.StatusCode != 206 || string(part) != "%PDF-" {
		t.Fatalf("range: %d %q", rr.StatusCode, part)
	}
}

func TestAdminPageIsServedWithSafeHeaders(t *testing.T) {
	srv, _ := newSite(t, "")
	resp, body := get(t, srv.URL+"/admin/")
	if resp.StatusCode != 200 || !strings.Contains(body, "Halcyon Admin") {
		t.Fatalf("/admin/: %d", resp.StatusCode)
	}
	if !strings.Contains(resp.Header.Get("Content-Security-Policy"), "default-src 'self'") {
		t.Error("the admin page needs the site's Content-Security-Policy")
	}
	if !strings.Contains(resp.Header.Get("X-Robots-Tag"), "noindex") || resp.Header.Get("Cache-Control") != "no-store" {
		t.Errorf("admin page headers: robots=%q cache=%q", resp.Header.Get("X-Robots-Tag"), resp.Header.Get("Cache-Control"))
	}
	for _, path := range []string{"/admin/admin.js", "/admin/admin.css"} {
		if r, _ := get(t, srv.URL+path); r.StatusCode != 200 {
			t.Errorf("%s: %d", path, r.StatusCode)
		}
	}
	// /admin (no slash) reaches the same page.
	client := &http.Client{CheckRedirect: func(*http.Request, []*http.Request) error { return http.ErrUseLastResponse }}
	r, err := client.Get(srv.URL + "/admin")
	if err != nil {
		t.Fatal(err)
	}
	r.Body.Close()
	// The Location is relative ("admin/"), which a browser resolves to /admin/.
	if loc := r.Header.Get("Location"); r.StatusCode != 301 || (loc != "admin/" && loc != "/admin/") {
		t.Errorf("/admin: %d -> %q, want a redirect to /admin/", r.StatusCode, loc)
	}
}