package main

import (
	"bufio"
	"context"
	"encoding/json"
	"errors"
	"fmt"
	"io"
	"os"
	"os/exec"
	"path/filepath"
	"regexp"
	"sort"
	"strings"
	"sync"
	"time"

	"git.eidonix.com/eidonix/cletus-plugins/sdk/manifest"
)

// report collects the outcome of each check.
type report struct {
	failures, warnings int
}

func (r *report) ok(name string) { fmt.Printf("ok    %s\n", name) }

func (r *report) fail(name, detail string) {
	r.failures++
	fmt.Printf("FAIL  %s\n%s", name, indent(detail))
}

func (r *report) warn(name, detail string) {
	r.warnings++
	fmt.Printf("warn  %s\n%s", name, indent(detail))
}

func indent(s string) string {
	s = strings.TrimRight(s, "\n")
	if s == "" {
		return ""
	}
	return "      " + strings.ReplaceAll(s, "\n", "\n      ") + "\n"
}

func runCheck(args []string) error {
	if len(args) > 0 {
		return errors.New("check takes no arguments; run it in the plugin's folder")
	}
	r := &report{}
	plugin, err := readPlugin(".")
	if err != nil {
		return err
	}

	if errs := plugin.Validate(); len(errs) > 0 {
		var b strings.Builder
		for _, e := range errs {
			fmt.Fprintln(&b, e)
		}
		r.fail("plugin.json", b.String())
	} else {
		r.ok("plugin.json")
	}
	checkFiles(r, plugin)
	own := ownGoFiles()
	checkSources(r, own)
	checkGoMod(r)
	if out, err := goRun(".", goEnv("", ""), "vet", "./..."); err != nil {
		r.fail("go vet", out)
	} else {
		r.ok("go vet")
	}
	checkImports(r, plugin)
	checkDependencies(r)
	for _, target := range [][2]string{{"darwin", "arm64"}, {"windows", "amd64"}} {
		name := "build " + target[0] + "/" + target[1]
		if out, err := goRun(".", goEnv(target[0], target[1]), "build", "-trimpath", "-o", os.DevNull, "./cmd/worker"); err != nil {
			r.fail(name, out)
		} else {
			r.ok(name)
		}
	}
	if out, err := goRun(".", goEnv("", ""), "test", "-count=1", "./..."); err != nil {
		r.fail("go test", out)
	} else {
		r.ok("go test")
	}
	optionalTool(r, "staticcheck", "./...")
	optionalTool(r, "govulncheck", "./...")
	checkRuntime(r, plugin)

	fmt.Println()
	switch {
	case r.failures > 0:
		return fmt.Errorf("%d check(s) failed, %d warning(s)", r.failures, r.warnings)
	case r.warnings > 0:
		fmt.Printf("All checks passed with %d warning(s). Explain each in docs/plan.md; reviewers read them.\n", r.warnings)
	default:
		fmt.Println("All checks passed.")
	}
	return nil
}

func checkFiles(r *report, plugin *manifest.Plugin) {
	var problems []string
	changelog, err := os.ReadFile("CHANGELOG.md")
	if err != nil {
		problems = append(problems, "CHANGELOG.md is missing")
	} else if !regexp.MustCompile(`(?m)^#+\s*v?` + regexp.QuoteMeta(plugin.Version) + `\b`).Match(changelog) {
		problems = append(problems, "CHANGELOG.md has no heading for version "+plugin.Version)
	}
	for _, path := range []string{"docs/plan.md", "docs/guide.md", "go.mod", "cmd/worker"} {
		if _, err := os.Stat(path); err != nil {
			problems = append(problems, path+" is missing")
		}
	}
	if plan, err := os.ReadFile("docs/plan.md"); err == nil {
		for _, perm := range plugin.Permissions {
			if !strings.Contains(string(plan), perm) {
				problems = append(problems, "docs/plan.md doesn't explain the "+perm+" permission")
			}
		}
	}
	if len(problems) > 0 {
		r.fail("repository files", strings.Join(problems, "\n"))
	} else {
		r.ok("repository files")
	}
}

// ownGoFiles lists the plugin's own Go files (not vendor/, not hidden folders).
func ownGoFiles() []string {
	var files []string
	_ = filepath.WalkDir(".", func(path string, d os.DirEntry, err error) error {
		if err != nil {
			return nil
		}
		if d.IsDir() && path != "." && (d.Name() == "vendor" || strings.HasPrefix(d.Name(), ".") || d.Name() == "node_modules") {
			return filepath.SkipDir
		}
		if !d.IsDir() && strings.HasSuffix(path, ".go") {
			files = append(files, path)
		}
		return nil
	})
	return files
}

var (
	secretRE   = regexp.MustCompile(`-----BEGIN [A-Z ]*PRIVATE KEY-----|AKIA[0-9A-Z]{16}|\bsk-[A-Za-z0-9_-]{20,}|\bghp_[A-Za-z0-9]{30,}|\bxox[abp]-[A-Za-z0-9-]{10,}`)
	fileOpRE   = regexp.MustCompile(`\bos\.(Open|OpenFile|ReadFile|WriteFile|Create|Remove|RemoveAll|ReadDir|Rename|Mkdir|MkdirAll)\(`)
	linknameRE = regexp.MustCompile(`//go:linkname`)
)

func checkSources(r *report, files []string) {
	var gofmtBad, cgo, secrets, linkname, fileOps []string
	if len(files) > 0 {
		out, _ := exec.Command("gofmt", append([]string{"-l"}, files...)...).Output()
		for _, line := range strings.Split(strings.TrimSpace(string(out)), "\n") {
			if line != "" {
				gofmtBad = append(gofmtBad, line)
			}
		}
	}
	_ = filepath.WalkDir(".", func(path string, d os.DirEntry, err error) error {
		if err != nil || d.IsDir() {
			if d != nil && d.IsDir() && path != "." && strings.HasPrefix(d.Name(), ".") {
				return filepath.SkipDir
			}
			return nil
		}
		info, err := d.Info()
		if err != nil || info.Size() > 4<<20 {
			return nil
		}
		data, err := os.ReadFile(path)
		if err != nil {
			return nil
		}
		text := string(data)
		vendored := strings.HasPrefix(filepath.ToSlash(path), "vendor/")
		if strings.HasSuffix(path, ".go") && regexp.MustCompile(`(?m)^import\s+"C"`).MatchString(text) {
			cgo = append(cgo, path)
		}
		if !vendored && secretRE.MatchString(text) {
			secrets = append(secrets, path)
		}
		if strings.HasSuffix(path, ".go") && !vendored {
			if linknameRE.MatchString(text) {
				linkname = append(linkname, path)
			}
			if !strings.HasSuffix(path, "_test.go") && fileOpRE.MatchString(text) {
				fileOps = append(fileOps, path)
			}
		}
		return nil
	})
	if len(gofmtBad) > 0 {
		r.fail("gofmt", "not formatted (run gofmt -w):\n"+strings.Join(gofmtBad, "\n"))
	} else {
		r.ok("gofmt")
	}
	if len(cgo) > 0 {
		r.fail("no cgo", "these files use cgo, which Cletus plugins can't:\n"+strings.Join(cgo, "\n"))
	} else {
		r.ok("no cgo")
	}
	if len(secrets) > 0 {
		r.fail("no secrets", "these files look like they hold a key or token:\n"+strings.Join(secrets, "\n"))
	} else {
		r.ok("no secrets")
	}
	if len(linkname) > 0 {
		r.fail("no go:linkname", strings.Join(linkname, "\n"))
	}
	if len(fileOps) > 0 {
		r.warn("direct file access", "these files open, write or delete files directly. Each path must come from\nhost.files.resolve, a dialog, or pluginsdk.DataDir(); anything else needs files.computer:\n"+strings.Join(fileOps, "\n"))
	}
}

func checkGoMod(r *report) {
	data, err := os.ReadFile("go.mod")
	if err != nil {
		return
	}
	text := string(data)
	var problems []string
	if regexp.MustCompile(`(?m)^\s*replace\b|=>`).MatchString(text) {
		problems = append(problems, "go.mod has replace directives; the store builds only from go.mod and vendor/")
	}
	if strings.Contains(text, "require") {
		if _, err := os.Stat("vendor/modules.txt"); err != nil {
			problems = append(problems, "vendor/ is missing; run go mod vendor and commit it")
		} else if out, err := goRun(".", goEnv("", ""), "build", "-mod=vendor", "-o", os.DevNull, "./cmd/worker"); err != nil {
			problems = append(problems, "vendor/ doesn't match go.mod; run go mod vendor:\n"+out)
		}
	}
	if len(problems) > 0 {
		r.fail("go.mod and vendor", strings.Join(problems, "\n"))
	} else {
		r.ok("go.mod and vendor")
	}
}

type goPackage struct {
	ImportPath string
	Imports    []string
	Standard   bool
	Module     *struct{ Path string }
}

func listPackages(args ...string) ([]goPackage, error) {
	cmd := exec.Command("go", append([]string{"list", "-json"}, args...)...)
	cmd.Env = goEnv("", "")
	out, err := cmd.Output()
	if err != nil {
		var exit *exec.ExitError
		if errors.As(err, &exit) {
			return nil, fmt.Errorf("%s", exit.Stderr)
		}
		return nil, err
	}
	var pkgs []goPackage
	dec := json.NewDecoder(strings.NewReader(string(out)))
	for {
		var p goPackage
		if err := dec.Decode(&p); err == io.EOF {
			break
		} else if err != nil {
			return nil, err
		}
		pkgs = append(pkgs, p)
	}
	return pkgs, nil
}

var netPackages = map[string]bool{"net": true, "net/http": true, "net/rpc": true, "net/smtp": true, "crypto/tls": true, "net/http/httputil": true}

func checkImports(r *report, plugin *manifest.Plugin) {
	own, err := listPackages("./...")
	if err != nil {
		r.fail("imports", err.Error())
		return
	}
	var failures, notes []string
	for _, p := range own {
		for _, imp := range p.Imports {
			switch {
			case imp == "plugin":
				failures = append(failures, p.ImportPath+" imports plugin (loading code at run time is not allowed)")
			case imp == "os/exec" && !plugin.Has("processes"):
				failures = append(failures, p.ImportPath+" imports os/exec but the plugin doesn't declare processes")
			case netPackages[imp] && !plugin.HasNet():
				failures = append(failures, p.ImportPath+" imports "+imp+" but the plugin declares no net permission")
			case imp == "unsafe" || imp == "reflect" || imp == "syscall" || strings.HasPrefix(imp, "golang.org/x/sys/"):
				notes = append(notes, p.ImportPath+" imports "+imp)
			}
		}
	}
	if len(failures) > 0 {
		r.fail("imports match permissions", strings.Join(failures, "\n"))
	} else {
		r.ok("imports match permissions")
	}
	if len(notes) > 0 {
		r.warn("low-level imports", "explain each in docs/plan.md:\n"+strings.Join(notes, "\n"))
	}
	deps, err := listPackages("-deps", "./cmd/worker")
	if err != nil {
		return
	}
	var depNotes []string
	for _, p := range deps {
		if p.Standard || p.Module == nil || isOwnModule(p.Module.Path) {
			continue
		}
		for _, imp := range p.Imports {
			if imp == "os/exec" && !plugin.Has("processes") || netPackages[imp] && !plugin.HasNet() {
				depNotes = append(depNotes, p.ImportPath+" imports "+imp)
			}
		}
	}
	if len(depNotes) > 0 {
		sort.Strings(depNotes)
		r.warn("dependencies that can start programs or connect", "your plugin doesn't declare this; make sure these code paths are never used:\n"+strings.Join(depNotes, "\n"))
	}
}

func isOwnModule(path string) bool {
	data, err := os.ReadFile("go.mod")
	if err != nil {
		return false
	}
	m := regexp.MustCompile(`(?m)^module\s+(\S+)`).FindStringSubmatch(string(data))
	return len(m) == 2 && m[1] == path
}

func checkDependencies(r *report) {
	f, err := os.Open("vendor/modules.txt")
	if err != nil {
		return
	}
	defer f.Close()
	var missing []string
	sc := bufio.NewScanner(f)
	for sc.Scan() {
		fields := strings.Fields(sc.Text())
		if len(fields) < 3 || fields[0] != "#" || fields[2] == "=>" {
			continue
		}
		dir := filepath.Join("vendor", filepath.FromSlash(fields[1]))
		if _, err := os.Stat(dir); err != nil {
			continue // a module with no packages in the build
		}
		if !hasLicense(dir) {
			missing = append(missing, fields[1]+" "+fields[2])
		}
	}
	if len(missing) > 0 {
		r.warn("dependency licences", "no licence file found; the store must be able to confirm each licence allows distribution:\n"+strings.Join(missing, "\n"))
	} else {
		r.ok("dependency licences present")
	}
}

func hasLicense(dir string) bool {
	entries, err := os.ReadDir(dir)
	if err != nil {
		return false
	}
	for _, e := range entries {
		name := strings.ToUpper(e.Name())
		if strings.HasPrefix(name, "LICENSE") || strings.HasPrefix(name, "LICENCE") || strings.HasPrefix(name, "COPYING") {
			return true
		}
	}
	return false
}

func optionalTool(r *report, tool string, args ...string) {
	if _, err := exec.LookPath(tool); err != nil {
		fmt.Printf("skip  %s (not installed; the store runs it)\n", tool)
		return
	}
	cmd := exec.Command(tool, args...)
	cmd.Env = goEnv("", "")
	out, err := cmd.CombinedOutput()
	if err != nil {
		r.fail(tool, string(out))
	} else {
		r.ok(tool)
	}
}

// checkRuntime starts the worker and compares its tools with plugin.json.
func checkRuntime(r *report, plugin *manifest.Plugin) {
	wd, _ := os.Getwd()
	bin, cleanup, err := buildWorker(wd)
	if err != nil {
		r.fail("worker starts", err.Error())
		return
	}
	defer cleanup()
	tmp, err := os.MkdirTemp("", "cletus-plugin-check-")
	if err != nil {
		r.fail("worker starts", err.Error())
		return
	}
	defer os.RemoveAll(tmp)
	log := &syncBuffer{}
	host := &testHost{plugin: plugin, filesDir: tmp, dataDir: filepath.Join(tmp, "data"), capabilities: map[string]bool{}, log: log}
	if err := host.start(bin); err != nil {
		r.fail("worker starts", err.Error()+"\n"+log.String())
		return
	}
	defer host.stop()
	r.ok("worker starts and answers the handshake")
	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
	defer cancel()
	var tools []struct {
		Def struct {
			Function struct {
				Name        string `json:"name"`
				Description string `json:"description"`
			} `json:"function"`
		} `json:"def"`
		Mutating         bool `json:"mutating"`
		RequiresApproval bool `json:"requires_approval"`
	}
	if err := host.call(ctx, "tools.list", nil, &tools); err != nil {
		r.fail("tools match plugin.json", "tools.list: "+err.Error())
		return
	}
	declared := map[string]manifest.Tool{}
	for _, t := range plugin.Tools {
		declared[t.Name] = t
	}
	var problems []string
	for _, t := range tools {
		name := t.Def.Function.Name
		d, ok := declared[name]
		switch {
		case !ok:
			problems = append(problems, "the worker offers "+name+", which plugin.json doesn't list")
		case d.Mutating != t.Mutating || d.RequiresApproval != t.RequiresApproval:
			problems = append(problems, name+": mutating or requires_approval differs between plugin.json and the worker")
		}
		if strings.TrimSpace(t.Def.Function.Description) == "" {
			problems = append(problems, name+" has no description")
		}
		delete(declared, name)
	}
	for name := range declared {
		problems = append(problems, "plugin.json lists "+name+", which the worker doesn't offer")
	}
	if len(problems) > 0 {
		sort.Strings(problems)
		r.fail("tools match plugin.json", strings.Join(problems, "\n"))
	} else {
		r.ok("tools match plugin.json")
	}
}

// syncBuffer is a strings.Builder safe for the worker's log and the host's
// call log to write at once.
type syncBuffer struct {
	mu sync.Mutex
	b  strings.Builder
}

func (s *syncBuffer) Write(p []byte) (int, error) {
	s.mu.Lock()
	defer s.mu.Unlock()
	return s.b.Write(p)
}

func (s *syncBuffer) String() string {
	s.mu.Lock()
	defer s.mu.Unlock()
	return s.b.String()
}