package main

import (
	"archive/tar"
	"bytes"
	"compress/gzip"
	"context"
	"io"
	"maps"
	"os"
	"path/filepath"
	"slices"
	"strings"
	"testing"

	"git.novox.be/novox/mesh-sdk/go/buildstep"
	"git.novox.be/novox/mesh-sdk/go/forgekey"
)

const bundleManifest = `{"module":"m","build":{"artifacts":[{"name":"tools","kind":"bundle","language":"typescript",` +
	`"entrypoints":["tools/index.js"],"loads":["tools/index.js"]%s}]}}`

// esbuildEffect stands in for esbuild's output: for each entry `.mesh-build/<a>/<path>.js` it writes the bundled file
// under --outdir, named as esbuild names it (the input without its extension, then .js or .mjs when --out-extension:.js=.mjs is given).
func esbuildEffect(t *testing.T) func(c call) {
	return func(c call) {
		if filepath.Base(c.name) != "esbuild" {
			return
		}
		var outdir, outbase, ext string
		var entries []string
		for _, a := range c.args {
			switch {
			case strings.HasPrefix(a, "--outdir="):
				outdir = strings.TrimPrefix(a, "--outdir=")
			case strings.HasPrefix(a, "--outbase="):
				outbase = strings.TrimPrefix(a, "--outbase=")
			case a == "--out-extension:.js=.mjs":
				ext = ".mjs"
			case !strings.HasPrefix(a, "--"):
				entries = append(entries, a)
			}
		}
		for _, e := range entries {
			rel := strings.TrimPrefix(strings.TrimPrefix(e, outbase), "/")
			// esbuild names an output after its input without the extension, and adds .js or the one asked for.
			rel = strings.TrimSuffix(rel, filepath.Ext(rel))
			if ext != "" {
				rel += ext
			} else {
				rel += ".js"
			}
			write(t, filepath.Join(c.dir, outdir, rel), "bundled "+rel, 0o644)
		}
	}
}

func buildArgs() map[string]any {
	return map[string]any{"workspace": "w1", "module": "modules/m", "artifact": "tools"}
}

func builtMachine(t *testing.T, extra string) (*Module, *fakeMachine, string) {
	m, f, work := newMachine(t)
	workspaceWith(t, work, map[string]string{"modules/m/module.json": strings.Replace(bundleManifest, "%s", extra, 1),
		"modules/m/tools/index.ts": "export {}"})
	f.effect = esbuildEffect(t)
	return m, f, work
}

// 1490/AC1: tsc and esbuild run with exactly the build agent's flags. The fixture is copied from mesh-controller
// origin/main: internal/builder/toolchain.go:143-147 (tsc: --module NodeNext --moduleResolution NodeNext --target
// ES2022 --rootDir .), builder.go:1637-1705 (--outDir .mesh-build/<artifact> and the sources) and :1971-2039 (esbuild:
// --bundle --platform=node --format=esm --target=node22 --outbase --outdir --log-level=warning, the createRequire
// banner, --out-extension:.js=.mjs for the launchers, --external:x). Where the build agent ran them in the toolchain
// image they run here with the toolchain's real paths, from the module's directory (env -C).
func TestTscAndEsbuildRunWithTheBuildAgentsFlags(t *testing.T) {
	m, f, work := builtMachine(t, `,"external":["pg"]`)
	if _, err := m.build(context.Background(), buildArgs()); err != nil {
		t.Fatal(err)
	}
	dir := filepath.Join(work, "w1", "stage-tools", "modules", "module")
	nm := filepath.Join(m.toolchainDir(), "node_modules")
	banner := "--banner:js=import { createRequire as __meshRequire } from 'node:module'; const require = __meshRequire(import.meta.url);"
	common := []string{"--bundle", "--platform=node", "--format=esm", "--target=node22",
		"--outbase=.mesh-build/tools", "--outdir=.mesh-build/tools.bundled", "--log-level=warning", banner, "--external:pg"}
	want := []string{
		"node " + nm + "/typescript/bin/tsc --module NodeNext --moduleResolution NodeNext --target ES2022 --rootDir . --outDir .mesh-build/tools tools/index.ts",
		nm + "/esbuild/bin/esbuild .mesh-build/tools/tools/index.js " + strings.Join(common, " "),
		nm + "/esbuild/bin/esbuild .mesh-build/tools/tools/index.serve.mjs " + strings.Join(common, " ") + " --out-extension:.js=.mjs",
	}
	if len(f.calls) != len(want) {
		t.Fatalf("%d commands ran, want %d: %v", len(f.calls), len(want), f.calls)
	}
	for i, c := range f.calls {
		if c.dir != dir || joined(c) != want[i] {
			t.Errorf("command %d: in %s ran\n%s\nwant in %s\n%s", i, c.dir, joined(c), dir, want[i])
		}
	}
}

// readArchive reads the archive a build pushed (ADR 0498: the packed file never stays on the node).
func readArchive(t *testing.T, r BuildResult) map[string]os.FileMode {
	t.Helper()
	raw := archiveOf(t, r)
	zr, err := gzip.NewReader(bytes.NewReader(raw))
	if err != nil {
		t.Fatal(err)
	}
	tr := tar.NewReader(zr)
	out := map[string]os.FileMode{}
	for {
		h, err := tr.Next()
		if err == io.EOF {
			return out
		}
		if err != nil {
			t.Fatal(err)
		}
		out[h.Name] = os.FileMode(h.Mode)
	}
}

// 1490: the step packs the bundle: the archive holds the bundled .js, the .serve.mjs launcher (executable) and the
// package.json that makes it an ES module, and the result is the archive's digest, the same for the same build.
func TestTheBundleIsPackedWithItsLauncherAndPackageJson(t *testing.T) {
	m, _, _ := builtMachine(t, ``)
	out, err := m.build(context.Background(), buildArgs())
	if err != nil {
		t.Fatal(err)
	}
	r := out.(BuildResult)
	if !strings.HasPrefix(r.Digest, "sha256:") || r.Bytes == 0 {
		t.Errorf("result = %+v", r)
	}
	if want := []string{"package.json", "tools/index.js", "tools/index.serve.mjs"}; !slices.Equal(r.Files, want) {
		t.Errorf("files = %v, want %v", r.Files, want)
	}
	modes := readArchive(t, r)
	if len(modes) != 3 || modes["tools/index.serve.mjs"]&0o111 == 0 {
		t.Errorf("archive = %v, want the three files with the launcher executable", modes)
	}
	again, err := m.build(context.Background(), buildArgs())
	if err != nil || again.(BuildResult).Digest != r.Digest {
		t.Errorf("a second build: %v, digest %v, want %s", err, again, r.Digest)
	}
	launcher, _ := os.ReadFile(filepath.Join(m.Work, "w1", "stage-tools", "modules", "module", ".mesh-build", "tools", "tools", "index.serve.mjs"))
	if !strings.Contains(string(launcher), `import { serveRegisteredOverStdio } from "@novox/mesh-sdk/stdio";`) || !strings.Contains(string(launcher), `await import("./index.js");`) {
		t.Errorf("launcher = %q", launcher)
	}
}

// 1490/AC3: no symlink is made anywhere in the workspace, with externals (whose packages are copied) or without.
func TestNoSymlinkIsMadeInTheWorkspace(t *testing.T) {
	for _, extra := range []string{``, `,"external":["nats"]`} {
		m, _, work := builtMachine(t, extra)
		if _, err := m.build(context.Background(), buildArgs()); err != nil {
			t.Fatal(err)
		}
		if links := symlinksUnder(t, filepath.Join(work, "w1")); len(links) != 0 {
			t.Errorf("symlinks in the workspace: %v", links)
		}
	}
}

// 1490: the bundle's SDK comes from the staging directory's node_modules, two levels above the module, and the packed bundle holds
// the toolchain's packages only when the artifact keeps one external, never typescript or esbuild.
func TestThePackagesAreCopiedBesideTheTreeAndIntoTheBundleOnlyForExternals(t *testing.T) {
	m, _, work := builtMachine(t, ``)
	out, err := m.build(context.Background(), buildArgs())
	if err != nil {
		t.Fatal(err)
	}
	nm := filepath.Join(work, "w1", "stage-tools", "node_modules")
	for _, p := range []string{"@novox/mesh-sdk/dist/stdio.js", "@types/node/index.d.ts", "nats/lib/nats.js"} {
		if _, err := os.Stat(filepath.Join(nm, p)); err != nil {
			t.Errorf("the workspace's node_modules lacks %s", p)
		}
	}
	for _, p := range []string{"typescript", "esbuild", "@esbuild"} {
		if _, err := os.Stat(filepath.Join(nm, p)); err == nil {
			t.Errorf("the toolchain's own %s was copied", p)
		}
	}
	for f := range readArchive(t, out.(BuildResult)) {
		if strings.HasPrefix(f, "node_modules") {
			t.Errorf("a bundle without externals carries %s", f)
		}
	}
	m, _, _ = builtMachine(t, `,"external":["nats"]`)
	out, _ = m.build(context.Background(), buildArgs())
	files := out.(BuildResult).Files
	if !slices.Contains(files, "node_modules/nats/lib/nats.js") || !slices.Contains(files, "node_modules/@novox/mesh-sdk/dist/stdio.js") {
		t.Errorf("files = %v, want the runtime packages beside the bundle", files)
	}
	for _, f := range files {
		if strings.Contains(f, "typescript") || strings.Contains(f, "esbuild") {
			t.Errorf("the bundle carries %s", f)
		}
	}
}

func TestAFailedCompilerFailsTheStepNamingIt(t *testing.T) {
	m, f, _ := builtMachine(t, ``)
	f.answer["tsc"] = forgekey.Ran{Status: 2, Stdout: tscTypeError}
	if _, err := m.build(context.Background(), buildArgs()); err == nil || !strings.Contains(err.Error(), "tsc for tools") || !strings.Contains(err.Error(), "tools/bad.ts") {
		t.Errorf("err = %v", err)
	}
}

func TestOnlyATypeScriptBundleOfTheModuleIsBuilt(t *testing.T) {
	m, _, _ := builtMachine(t, ``)
	for _, a := range []string{"nope", ""} {
		args := buildArgs()
		args["artifact"] = a
		if _, err := m.build(context.Background(), args); err == nil {
			t.Errorf("artifact %q was built", a)
		}
	}
}

// 1490 (review 7): the build agent runs a module mounted at /app/modules/module with the toolchain's packages at
// /app/node_modules (mesh-controller builder.go `within`), so esbuild writes the path comments of what it inlines
// relative to the module's directory as `../../node_modules/...`. The step builds at that depth: in a staging
// directory whose module directory has the packages two levels above it, whatever the module's place in the
// repository, so the bundle's bytes (and its digest) equal the build agent's.
func TestTheBuildRunsWithThePackagesTwoLevelsAboveTheModule(t *testing.T) {
	for _, module := range []string{"modules/m", "."} {
		m, f, work := newMachine(t)
		files := map[string]string{"module.json": strings.Replace(bundleManifest, "%s", "", 1), "tools/index.ts": "export {}"}
		if module != "." {
			files = map[string]string{"modules/m/module.json": strings.Replace(bundleManifest, "%s", "", 1), "modules/m/tools/index.ts": "export {}"}
		}
		workspaceWith(t, work, files)
		f.effect = esbuildEffect(t)
		args := buildArgs()
		args["module"] = module
		if _, err := m.build(context.Background(), args); err != nil {
			t.Fatalf("%s: %v", module, err)
		}
		for _, c := range f.calls {
			rel, err := filepath.Rel(c.dir, filepath.Join(c.dir, "..", "..", "node_modules"))
			if err != nil || rel != "../../node_modules" {
				t.Fatalf("%s: relative path %q (%v)", module, rel, err)
			}
			if _, err := os.Stat(filepath.Join(c.dir, "..", "..", "node_modules", "@novox", "mesh-sdk", "dist", "stdio.js")); err != nil {
				t.Errorf("%s: %s ran in %s, which has no packages at ../../node_modules: %v", module, filepath.Base(c.name), c.dir, err)
			}
			if filepath.Base(c.dir) != "module" || filepath.Base(filepath.Dir(c.dir)) != "modules" {
				t.Errorf("%s: ran in %s, want .../modules/module", module, c.dir)
			}
		}
		if !strings.HasPrefix(f.calls[0].dir, filepath.Join(work, "w1")) {
			t.Errorf("%s: staged outside the workspace: %s", module, f.calls[0].dir)
		}
	}
}

// R4e: the launchers a build writes are mesh-sdk's one rule (buildstep.Launchers), the names the controller reads a bundle
// by; an entrypoint that is not JavaScript gets none.
func TestTheLaunchersAreTheSDKsRule(t *testing.T) {
	a := artifact{Language: "typescript", Entrypoints: []string{"tools/index.js", "web/server.js", "assets/x.css"}}
	got, err := writeLaunchers(t.TempDir(), a)
	if err != nil {
		t.Fatal(err)
	}
	if want := buildstep.Launchers(a.Language, a.Entrypoints); !maps.Equal(got, want) || len(got) != 2 {
		t.Errorf("launchers %v, mesh-sdk's rule %v", got, want)
	}
}