// Command imageplace refuses an image artifact whose Dockerfile is not a file inside its own module's directory
// (novox/hq ADR 0487 §1, issue 1707): the image builder builds a module from that module's directory alone, so
// a `from` that leaves it (../other/Dockerfile) or names a file that is not there could never build.
//
//	go run . <catalogue root>
//
// Exits 1 on a finding.
package main

import (
	"encoding/json"
	"fmt"
	"os"
	"path/filepath"
	"sort"
	"strings"
)

// Finding is one image refused: Module's artifact Artifact names From, and Why says what is wrong with it.
type Finding struct {
	Module, Artifact, From, Why string
}

// Check reads every manifest under root/modules and answers which images it refuses.
func Check(root string) ([]Finding, error) {
	manifests, err := filepath.Glob(filepath.Join(root, "modules", "*", "module.json"))
	if err != nil {
		return nil, err
	}
	sort.Strings(manifests)
	var out []Finding
	for _, path := range manifests {
		raw, err := os.ReadFile(path)
		if err != nil {
			return nil, err
		}
		var m struct {
			Module string `json:"module"`
			Build  struct {
				Artifacts []struct {
					Name string `json:"name"`
					Kind string `json:"kind"`
					From string `json:"from"`
				} `json:"artifacts"`
			} `json:"build"`
		}
		if err := json.Unmarshal(raw, &m); err != nil {
			return nil, fmt.Errorf("%s: %w", path, err)
		}
		dir := filepath.Dir(path)
		for _, a := range m.Build.Artifacts {
			if a.Kind != "image" {
				continue
			}
			f := Finding{Module: m.Module, Artifact: a.Name, From: a.From}
			clean := filepath.Clean(a.From)
			switch {
			case a.From == "" || filepath.IsAbs(clean) || clean == ".." || strings.HasPrefix(clean, ".."+string(filepath.Separator)):
				f.Why = "is not a path inside the module's own directory"
			default:
				info, err := os.Stat(filepath.Join(dir, clean))
				if err != nil || info.IsDir() {
					f.Why = "is not a file in the module's directory"
				}
			}
			if f.Why != "" {
				out = append(out, f)
			}
		}
	}
	return out, nil
}

func main() {
	root := "."
	if len(os.Args) > 1 {
		root = os.Args[1]
	}
	found, err := Check(root)
	if err != nil {
		fmt.Fprintln(os.Stderr, err)
		os.Exit(1)
	}
	for _, f := range found {
		fmt.Printf("%s: image %s builds from %q, which %s (novox/hq ADR 0487 §1)\n", f.Module, f.Artifact, f.From, f.Why)
	}
	if len(found) > 0 {
		os.Exit(1)
	}
	fmt.Println("imageplace: every image builds from a Dockerfile in its own module's directory")
}