// Command environment refuses a module's code reading a MESH_* word of its environment that nothing gives it: not its
// manifest, and not the node-engine or the tool runner for every process (the lead's ruling on A3n, issue 1966).
//
// A MESH_* word is the mesh's contract with a module's process: the manifest sets it (an `env` of a build artifact or a
// resource, an `environment`'s `variables`, a `NAME=` line of a file the module ships for an env-file), or the mesh gives
// it to every process (Given). A word read and set by nothing is a contract nobody keeps: the program runs on its
// default or on nothing, and says so to nobody (MESH_REGISTRY_REACH answered every published reference without its
// registry; MESH_CONFIG_CALLERS held every window shut). Found here, it is refused: the code reads what the mesh gives
// (a manifest word, a config value through its tools, a seat's name), or the manifest sets it.
//
// A read is `os.Getenv` or `os.LookupEnv` of a literal or of a constant of the same directory (Go), and `env.MESH_*` or
// `env["MESH_*"]` (TypeScript, `process.env` included); tests, test directories, node_modules and dist are not read. The
// modules still reading such a word are listed in the file `unset` beside this check, `<module> <WORD>` a line, until
// each is fixed: a line no longer found is refused, so the list only shrinks.
//
//	go run . <catalogue root>
//
// Exits 1 on a finding.
package main

import (
	"bufio"
	"encoding/json"
	"fmt"
	"io/fs"
	"os"
	"path/filepath"
	"regexp"
	"sort"
	"strings"
)

// Given is every MESH_* word the mesh gives a module's processes whatever their manifest says, and who gives it.
var Given = map[string]string{
	// The tool runner, to every bundle and to a module's own runtime (mesh-tools node-tools runtime.BundleEnv).
	"MESH_MODULE":        "the tool runner",
	"MESH_SERVED_MODULE": "the tool runner",
	"MESH_NODE":          "the tool runner",
	// The node-engine, to the tool runner it runs as the operator's account; its bundles inherit them (mesh-host
	// compose/resolution runtime.go).
	"MESH_OPERATOR_ACCOUNT": "the node-engine",
	"MESH_OPERATOR_HOME":    "the node-engine",
	// The node-engine, to every module that yields to the node's builds (ADR 0553 §3; catalogue.BuildCPUShareWord).
	"MESH_BUILD_CPU_SHARE": "the node-engine",
}

const listFile = "unset"

var (
	goRead  = regexp.MustCompile(`os\.(?:Getenv|LookupEnv)\(\s*(?:"(MESH_[A-Z0-9_]+)"|([A-Za-z_][A-Za-z0-9_]*))\s*\)`)
	goConst = regexp.MustCompile(`\b([A-Za-z_][A-Za-z0-9_]*)\s*(?:string\s*)?=\s*"(MESH_[A-Z0-9_]+)"`)
	tsRead  = regexp.MustCompile(`\benv(?:\.|\[\s*["'])(MESH_[A-Z0-9_]+)`)
	envLine = regexp.MustCompile(`(?m)^\s*(?:export\s+)?(MESH_[A-Z0-9_]+)=`)
)

// skipped are the directories whose code no process of the module runs.
var skipped = map[string]bool{"node_modules": true, "dist": true, "test": true, "testdata": true, ".git": true}

// Check answers, per module, each MESH_* word its code reads that its manifest does not set and the mesh does not
// give, with the files reading it.
func Check(root string) (map[string]map[string][]string, error) {
	manifests, err := filepath.Glob(filepath.Join(root, "modules", "*", "module.json"))
	if err != nil {
		return nil, err
	}
	sort.Strings(manifests)
	out := map[string]map[string][]string{}
	for _, path := range manifests {
		dir := filepath.Dir(path)
		raw, err := os.ReadFile(path)
		if err != nil {
			return nil, err
		}
		var manifest any
		if err := json.Unmarshal(raw, &manifest); err != nil {
			return nil, fmt.Errorf("%s: %w", path, err)
		}
		set := map[string]bool{}
		setBy(manifest, set)
		reads := map[string]map[string]bool{}
		consts := map[string]map[string]string{} // directory -> constant -> word
		var goFiles []string
		err = filepath.WalkDir(dir, func(p string, d fs.DirEntry, err error) error {
			if err != nil {
				return err
			}
			if d.IsDir() {
				if p != dir && skipped[d.Name()] {
					return filepath.SkipDir
				}
				return nil
			}
			name := d.Name()
			text, err := os.ReadFile(p)
			if err != nil {
				return err
			}
			rel, _ := filepath.Rel(dir, p)
			rel = filepath.ToSlash(rel)
			switch {
			case strings.HasSuffix(name, "_test.go"), strings.HasSuffix(name, ".test.ts"), strings.HasSuffix(name, ".d.ts"):
			case strings.HasSuffix(name, ".go"):
				goFiles = append(goFiles, p)
				c := consts[filepath.Dir(p)]
				if c == nil {
					c = map[string]string{}
					consts[filepath.Dir(p)] = c
				}
				for _, m := range goConst.FindAllStringSubmatch(string(text), -1) {
					c[m[1]] = m[2]
				}
			case strings.HasSuffix(name, ".ts"):
				for _, m := range tsRead.FindAllStringSubmatch(string(text), -1) {
					read(reads, m[1], rel)
				}
			case name != "module.json":
				// A file the module ships: a NAME= line is a word an env-file gives.
				for _, m := range envLine.FindAllStringSubmatch(string(text), -1) {
					set[m[1]] = true
				}
			}
			return nil
		})
		if err != nil {
			return nil, err
		}
		for _, p := range goFiles {
			text, _ := os.ReadFile(p)
			rel, _ := filepath.Rel(dir, p)
			for _, m := range goRead.FindAllStringSubmatch(string(text), -1) {
				word := m[1]
				if word == "" {
					word = consts[filepath.Dir(p)][m[2]]
				}
				if word != "" {
					read(reads, word, filepath.ToSlash(rel))
				}
			}
		}
		module := filepath.Base(dir)
		for word, files := range reads {
			if set[word] || Given[word] != "" {
				continue
			}
			if out[module] == nil {
				out[module] = map[string][]string{}
			}
			for f := range files {
				out[module][word] = append(out[module][word], f)
			}
			sort.Strings(out[module][word])
		}
	}
	return out, nil
}

func read(reads map[string]map[string]bool, word, file string) {
	if reads[word] == nil {
		reads[word] = map[string]bool{}
	}
	reads[word][file] = true
}

// setBy collects the words a manifest sets: every key of an `env` object and of an `environment`'s `variables`.
func setBy(v any, set map[string]bool) {
	switch v := v.(type) {
	case map[string]any:
		for k, e := range v {
			if m, ok := e.(map[string]any); ok && (k == "env" || k == "variables") {
				for word := range m {
					set[word] = true
				}
			}
			setBy(e, set)
		}
	case []any:
		for _, e := range v {
			setBy(e, set)
		}
	}
}

// Listed is the list's `<module> <WORD>` lines; a line starting with # and a blank line are not entries.
func Listed(path string) (map[string]bool, error) {
	f, err := os.Open(path)
	if err != nil {
		return nil, err
	}
	defer f.Close()
	out := map[string]bool{}
	s := bufio.NewScanner(f)
	for s.Scan() {
		line := strings.Join(strings.Fields(s.Text()), " ")
		if line == "" || strings.HasPrefix(line, "#") {
			continue
		}
		out[line] = true
	}
	return out, s.Err()
}

// Judge answers the reads not on the list (refused) and the list's lines no read stands for (stale).
func Judge(found map[string]map[string][]string, listed map[string]bool) (refused, stale []string) {
	seen := map[string]bool{}
	for module, words := range found {
		for word := range words {
			line := module + " " + word
			seen[line] = true
			if !listed[line] {
				refused = append(refused, line)
			}
		}
	}
	for line := range listed {
		if !seen[line] {
			stale = append(stale, line)
		}
	}
	sort.Strings(refused)
	sort.Strings(stale)
	return refused, stale
}

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)
	}
	listed, err := Listed(listFile)
	if err != nil {
		fmt.Fprintln(os.Stderr, err)
		os.Exit(1)
	}
	refused, stale := Judge(found, listed)
	for _, line := range refused {
		module, word, _ := strings.Cut(line, " ")
		fmt.Printf("%s reads %s (%s), which its manifest does not set and the mesh gives no process: set it in the "+
			"manifest, or read what the mesh gives\n", module, word, strings.Join(found[module][word], ", "))
	}
	for _, line := range stale {
		fmt.Printf("checks/environment/%s names %q, which no code reads unset any more: take it off the list\n", listFile, line)
	}
	if len(refused) > 0 || len(stale) > 0 {
		os.Exit(1)
	}
	fmt.Printf("environment: every MESH_* word a module reads is set by its manifest or given by the mesh (%d still listed)\n", len(listed))
}