// 分层依赖棘轮：backend internal 包与前端目录组之间的导入边。
// 相对基线多出来的边失败；基线里已经消失的边只告警。
package main

import (
	"bufio"
	"bytes"
	"encoding/json"
	"flag"
	"fmt"
	"go/parser"
	"go/token"
	"os"
	"path/filepath"
	"sort"
	"strings"
)

func main() {
	root := flag.String("root", ".", "repository root")
	baseline := flag.String("baseline", "policy/architecture-baseline.json", "recorded edges")
	write := flag.Bool("write", false, "rewrite the baseline from the current tree")
	inject := flag.String("inject", "", "extra edge from->to, used to prove a new edge fails")
	flag.Parse()

	if err := checkPolicy(*root); err != nil {
		fmt.Fprintf(os.Stderr, "architecture: %v\n", err)
		os.Exit(1)
	}
	edges, err := collect(*root)
	if err != nil {
		fmt.Fprintf(os.Stderr, "architecture: %v\n", err)
		os.Exit(1)
	}
	if *inject != "" {
		parts := strings.Split(*inject, "->")
		if len(parts) != 2 || parts[0] == "" || parts[1] == "" {
			fmt.Fprintln(os.Stderr, "architecture: -inject must be from->to")
			os.Exit(2)
		}
		edges = append(edges, parts[0]+" "+parts[1])
	}
	sort.Strings(edges)
	edges = unique(edges)
	if *write {
		raw, err := json.MarshalIndent(edges, "", "  ")
		if err != nil {
			fmt.Fprintf(os.Stderr, "architecture: %v\n", err)
			os.Exit(1)
		}
		raw = append(raw, '\n')
		if err := os.WriteFile(*baseline, raw, 0o644); err != nil {
			fmt.Fprintf(os.Stderr, "architecture: %v\n", err)
			os.Exit(1)
		}
		fmt.Printf("wrote %d edges\n", len(edges))
		return
	}
	recorded, err := readBaseline(*baseline)
	if err != nil {
		fmt.Fprintf(os.Stderr, "architecture: %v\n", err)
		os.Exit(1)
	}
	observed := map[string]bool{}
	for _, e := range edges {
		observed[e] = true
	}
	var fresh, stale []string
	for _, e := range edges {
		if !recorded[e] {
			fresh = append(fresh, e)
		}
	}
	for e := range recorded {
		if !observed[e] {
			stale = append(stale, e)
		}
	}
	sort.Strings(stale)
	if len(stale) > 0 {
		fmt.Fprintln(os.Stderr, "warn: architecture edges no longer present; delete them from the baseline")
		for _, e := range stale {
			fmt.Fprintln(os.Stderr, " ", e)
		}
	}
	if len(fresh) > 0 {
		fmt.Fprintln(os.Stderr, "architecture: new dependency edges")
		for _, e := range fresh {
			fmt.Fprintln(os.Stderr, " ", e)
		}
		os.Exit(1)
	}
	fmt.Printf("architecture ok (%d edges)\n", len(edges))
}

func readBaseline(path string) (map[string]bool, error) {
	raw, err := os.ReadFile(path)
	if err != nil {
		return nil, err
	}
	var list []string
	if err := json.Unmarshal(raw, &list); err != nil {
		return nil, err
	}
	out := map[string]bool{}
	for _, e := range list {
		out[e] = true
	}
	return out, nil
}

func checkPolicy(root string) error {
	raw, err := os.ReadFile(filepath.Join(root, "policy/architecture.yaml"))
	if err != nil {
		return err
	}
	text := string(raw)
	for _, need := range []string{"modules/backend/internal", "modules/frontend/src", "components"} {
		if !strings.Contains(text, need) {
			return fmt.Errorf("policy/architecture.yaml missing %s", need)
		}
	}
	return nil
}

func collect(root string) ([]string, error) {
	var edges []string
	be, err := backendEdges(filepath.Join(root, "modules/backend/internal"))
	if err != nil {
		return nil, err
	}
	edges = append(edges, be...)
	fe, err := frontendEdges(filepath.Join(root, "modules/frontend/src"))
	if err != nil {
		return nil, err
	}
	edges = append(edges, fe...)
	return edges, nil
}

func backendEdges(dir string) ([]string, error) {
	var edges []string
	err := filepath.WalkDir(dir, func(path string, d os.DirEntry, err error) error {
		if err != nil || d.IsDir() {
			return nil
		}
		if !strings.HasSuffix(path, ".go") || strings.HasSuffix(path, "_test.go") {
			return nil
		}
		from := backendNode(dir, path)
		if from == "" {
			return nil
		}
		fset := token.NewFileSet()
		f, err := parser.ParseFile(fset, path, nil, parser.ImportsOnly)
		if err != nil {
			return err
		}
		for _, imp := range f.Imports {
			p := strings.Trim(imp.Path.Value, `"`)
			const prefix = "agent-system-backend/internal/"
			if !strings.HasPrefix(p, prefix) {
				continue
			}
			rest := strings.TrimPrefix(p, prefix)
			seg := strings.Split(rest, "/")[0]
			to := "backend/" + seg
			if to == from {
				continue
			}
			edges = append(edges, from+" "+to)
		}
		return nil
	})
	return edges, err
}

func backendNode(root, path string) string {
	rel, err := filepath.Rel(root, path)
	if err != nil {
		return ""
	}
	seg := strings.Split(filepath.ToSlash(rel), "/")[0]
	if seg == "" || seg == "." {
		return ""
	}
	return "backend/" + seg
}

func frontendEdges(src string) ([]string, error) {
	var edges []string
	err := filepath.WalkDir(src, func(path string, d os.DirEntry, err error) error {
		if err != nil || d.IsDir() {
			return nil
		}
		if !strings.HasSuffix(path, ".ts") && !strings.HasSuffix(path, ".tsx") {
			return nil
		}
		if strings.HasSuffix(path, ".d.ts") {
			return nil
		}
		from := frontendNode(src, path)
		text, err := os.ReadFile(path)
		if err != nil {
			return err
		}
		for _, spec := range importSpecs(text) {
			if !strings.HasPrefix(spec, ".") {
				continue
			}
			target := filepath.Clean(filepath.Join(filepath.Dir(path), spec))
			if !strings.HasPrefix(target, src) {
				continue
			}
			to := frontendNode(src, target)
			if to == "" || to == from {
				continue
			}
			edges = append(edges, from+" "+to)
		}
		return nil
	})
	return edges, err
}

func frontendNode(src, path string) string {
	rel, err := filepath.Rel(src, path)
	if err != nil {
		return ""
	}
	rel = filepath.ToSlash(rel)
	if strings.HasPrefix(rel, "components/") || rel == "components" {
		return "frontend/components"
	}
	return "frontend/app"
}

func importSpecs(src []byte) []string {
	var specs []string
	sc := bufio.NewScanner(bytes.NewReader(src))
	for sc.Scan() {
		line := sc.Text()
		for _, marker := range []string{"from '", `from "`, "import('", `import("`} {
			i := strings.Index(line, marker)
			if i < 0 {
				continue
			}
			rest := line[i+len(marker):]
			quote := marker[len(marker)-1]
			end := strings.IndexByte(rest, quote)
			if end > 0 {
				specs = append(specs, rest[:end])
			}
		}
	}
	return specs
}

func unique(in []string) []string {
	if len(in) == 0 {
		return in
	}
	out := in[:1]
	for _, s := range in[1:] {
		if s != out[len(out)-1] {
			out = append(out, s)
		}
	}
	return out
}