package main

import (
	"errors"
	"fmt"
	"io"
	"os"
	"path/filepath"
	"sort"

	"github.com/novox/mesh-controller/internal/catalogue"
)

// moduleCheck judges manifests where they are written, with no mesh (novox/hq ADR 0037, issue 148).
//
// **The same functions registration runs, and nothing the command line adds** (ADR 0035): the strict
// parse with every per-manifest problem, then the rules no single manifest can be judged against,
// over exactly the manifests given. Somebody describing their own application in their own
// repository runs this before pushing and finds out there, rather than when a running mesh refuses
// the registration or, later, when a machine applies something that resolved and should not have.
//
// **What it cannot know without a store, it says.** The mesh's own seat set is the store's (ADR
// 0122); this binary carries a compiled copy that the store overrides when loaded, so a claim on a
// mesh seat is judged fully only at registration. A seat another module declares is unknown unless
// that module's manifest is passed too. Both are printed as a note, not as a problem — a check that
// refused what it could not see would teach people to ignore it.
func moduleCheck(paths []string, out io.Writer) error {
	if len(paths) == 0 {
		return errors.New("module check <manifest.json>... — one file per module; pass every " +
			"manifest of a repository together so the rules between them are checked too")
	}
	shelf := catalogue.Shelf{}
	faulted := map[string]bool{}
	failed := 0
	for _, path := range paths {
		raw, err := os.ReadFile(path)
		if err != nil {
			fmt.Fprintf(out, "%s: %v\n", path, err)
			failed++
			continue
		}
		m, err := catalogue.ParseManifest(raw)
		if err != nil {
			fmt.Fprintf(out, "%s: %v\n", path, err)
			failed++
			continue
		}
		if first, twice := shelf[m.Module]; twice {
			_ = first
			fmt.Fprintf(out, "%s: %s was already given; two manifests name one module\n", path, m.Module)
			failed++
			continue
		}
		// A definition names no installation (novox/hq ADR 0112, ADR 0155): judged here and in the
		// catalogue-wide test, not yet at registration, while the declared exceptions shrink.
		if named := catalogue.InstallationProblems(m); len(named) > 0 {
			for _, p := range named {
				fmt.Fprintf(out, "%s: %s\n", path, p)
			}
			failed += len(named)
			faulted[m.Module] = true
		}
		shelf[m.Module] = m
	}

	// Between the manifests: a seat declared twice, a use of a seat nothing declares, a claim on
	// a seat that does not exist. Run only over what parsed, because a problem inside one manifest
	// has already been said and would be said again here in a worse form.
	problems := catalogue.CatalogueProblems(shelf)
	sort.Strings(problems)
	for _, p := range problems {
		fmt.Fprintln(out, p)
	}
	failed += len(problems)

	var names []string
	for name := range shelf {
		names = append(names, name)
	}
	sort.Strings(names)
	for _, name := range names {
		m := shelf[name]
		if faulted[name] {
			continue
		}
		fmt.Fprintf(out, "%s: ok", name)
		if n := len(m.Tools); n > 0 {
			fmt.Fprintf(out, ", %d tool(s)", n)
		}
		if len(m.Invokes) > 0 {
			fmt.Fprintf(out, ", invokes %s", joinInvokes(m.Invokes))
		}
		fmt.Fprintln(out)
	}
	if failed > 0 {
		return fmt.Errorf("%d problem(s) in %d manifest(s)", failed, len(paths))
	}
	fmt.Fprintf(out, "%d manifest(s) checked. Judged against the seats this binary carries; a claim on "+
		"one of the mesh's own seats is judged fully at registration, and a seat declared by a "+
		"module not given here reads as unknown\n", len(paths))
	return nil
}

func joinInvokes(invokes []string) string {
	if len(invokes) == 1 && invokes[0] == "*" {
		return "every tool"
	}
	s := ""
	for i, t := range invokes {
		if i > 0 {
			s += ", "
		}
		s += t
	}
	return s
}

// manifestsUnder lists every module.json below a directory, for `module check <dir>`.
func manifestsUnder(dir string) ([]string, error) {
	var found []string
	err := filepath.WalkDir(dir, func(path string, d os.DirEntry, err error) error {
		if err != nil {
			return err
		}
		if d.IsDir() && (d.Name() == "node_modules" || d.Name() == ".git" || d.Name() == "dist") {
			return filepath.SkipDir
		}
		if !d.IsDir() && d.Name() == "module.json" {
			found = append(found, path)
		}
		return nil
	})
	sort.Strings(found)
	return found, err
}