//go:build ignore

// Prints src/lib/dkc/testing/mutation-texts.json: the text of the error that
// capsule.Open of the Go reference gives for every case of
// testdata/vectors/mutations.json, or "ok" for a capsule that opens, so that
// vectors.test.ts requires the same text of open, byte for byte, and not
// only the same code and step (plan of format 3 in datekeys-ts, step 3).
//
// Each case is replayed as internal/testkit replays the corpus
// (MutationInput.Open), which a module outside the reference cannot import:
// the Quicknet profile pinned, or no profile for the registry "empty"; a
// source that answers every request with the release of the case, or with
// "testkit: no release" and ERR_RELEASE_UNAVAILABLE, given as
// OpenOptions.Release when the source of the case is "supplied", a release
// object with the Quicknet chain unless the case names another, and as
// OpenOptions.Source when it is "network", which verifies the release and
// discards it (spec v0.15, §63 step 9); the .dkk
// decoded before, as OpenOptions.AccessKey; the identities of the case; the
// extensions of the case, known at (id, version) and whose data is valid
// only when it is valid_data, with the texts of testkit.KnownExtensions; a
// sink that discards the files; and the clock of the case. The code of every
// error is checked against the corpus: a mismatch panics.
//
// Run it from a scratch module that requires the reference implementation
// (replace g.activething.com/go/DateKeys => ../datekeys-go, GOFLAGS=-mod=mod
// and the go directive of the reference, so that its toolchain is used),
// passing the testdata directory of this repository:
//
//	go run mutation-go-texts.go ../datekeys-ts/testdata > mutation-texts.json
package main

import (
	"bytes"
	"context"
	"encoding/hex"
	"encoding/json"
	"fmt"
	"io"
	"os"
	"path/filepath"
	"time"

	"filippo.io/age"
	datekeys "g.activething.com/go/DateKeys"
	"g.activething.com/go/DateKeys/accesskey"
	"g.activething.com/go/DateKeys/capsule"
	"g.activething.com/go/DateKeys/extension"
	"g.activething.com/go/DateKeys/profile"
	"g.activething.com/go/DateKeys/provider"
)

type corpus struct {
	Spec  string `json:"spec"`
	Cases []struct {
		Name string `json:"name"`
		DKC  struct {
			Base  string              `json:"base"`
			Edits [][]json.RawMessage `json:"edits"`
		} `json:"dkc"`
		DKK        string   `json:"dkk"`
		Identities []string `json:"identities"`
		Release    *struct {
			Round     uint64 `json:"round"`
			Signature string `json:"signature"`
			ChainHash string `json:"chain_hash"`
		} `json:"release"`
		Source     string `json:"source"`
		Now        string `json:"now"`
		Registry   string `json:"registry"`
		Extensions []struct {
			ID        string `json:"id"`
			Version   uint64 `json:"version"`
			ValidData string `json:"valid_data"`
		} `json:"extensions"`
		Error string `json:"error"`
		Step  int    `json:"step"`
	} `json:"cases"`
}

type caseOut struct {
	Name string `json:"name"`
	Text string `json:"text"`
}

type output struct {
	Description string    `json:"description"`
	Generator   string    `json:"generator"`
	Spec        string    `json:"spec"`
	Cases       []caseOut `json:"cases"`
}

// known is testkit.KnownExtensions: an extension.Registry and
// extension.DataValidator with the same texts.
type known []struct {
	id      string
	version uint64
	valid   []byte
}

func (k known) find(id string, version uint64) int {
	for i := range k {
		if k[i].id == id && k[i].version == version {
			return i
		}
	}
	return -1
}

func (k known) Known(id string, version uint64) bool { return k.find(id, version) >= 0 }

func (k known) ValidateData(e extension.Extension) error {
	i := k.find(e.ID, e.Version)
	if i < 0 {
		return fmt.Errorf("extension %s version %d is not known", e.ID, e.Version)
	}
	if !bytes.Equal(k[i].valid, e.Data) {
		return fmt.Errorf("data %x is not %x", e.Data, k[i].valid)
	}
	return nil
}

// source is testkit's singleSource: as a network source, Fetch verifies the
// release and discards it when it breaks a rule of step 10; as a release in
// hand, Supply hands over its release object, with the chain of the pinned
// profile unless the release names another.
type source struct{ release *provider.Release }

func (s source) Fetch(_ context.Context, p *profile.Profile, c provider.Condition) (provider.Release, error) {
	if s.release == nil {
		return provider.Release{}, fmt.Errorf("testkit: no release: %w", datekeys.ErrReleaseUnavailable)
	}
	if err := provider.Verify(p, c, *s.release); err != nil {
		return provider.Release{}, fmt.Errorf("testkit: the release is discarded: %v: %w", err, datekeys.ErrReleaseUnavailable)
	}
	return *s.release, nil
}

func (s source) Supply(p *profile.Profile, _ provider.Condition) ([]byte, error) {
	if s.release == nil {
		return nil, fmt.Errorf("testkit: no release: %w", datekeys.ErrReleaseUnavailable)
	}
	r := *s.release
	if r.ChainHash == nil {
		r.ChainHash = p.ChainHash[:]
	}
	return provider.EncodeRelease(r)
}

// discard is testkit's DiscardSink.
type discard struct{}

func (discard) Begin(*capsule.Head) error          { return nil }
func (discard) Create(int) (io.WriteCloser, error) { return nopCloser{io.Discard}, nil }
func (discard) Commit() error                      { return nil }
func (discard) Abort()                             {}

type nopCloser struct{ io.Writer }

func (nopCloser) Close() error { return nil }

func must[T any](v T, err error) T {
	if err != nil {
		panic(err)
	}
	return v
}

// applyEdits is the reading of README "Edited files": [at, delete, insert]
// on the offsets of the unmodified base, sorted and not overlapping.
func applyEdits(base []byte, edits [][]json.RawMessage) []byte {
	var out []byte
	pos := 0
	for _, e := range edits {
		var at, del int
		var insert string
		if len(e) != 3 || json.Unmarshal(e[0], &at) != nil || json.Unmarshal(e[1], &del) != nil || json.Unmarshal(e[2], &insert) != nil {
			panic("an edit is [at, delete, insert]")
		}
		if at < pos || at+del > len(base) {
			panic("edits out of order or beyond the base")
		}
		out = append(append(out, base[pos:at]...), must(hex.DecodeString(insert))...)
		pos = at + del
	}
	return append(out, base[pos:]...)
}

func main() {
	dir := os.Args[1]
	var c corpus
	if err := json.Unmarshal(must(os.ReadFile(filepath.Join(dir, "vectors", "mutations.json"))), &c); err != nil {
		panic(err)
	}
	out := output{
		Description: "The text of the error of capsule.Open for every case of testdata/vectors/mutations.json, or ok for a capsule that opens; see the header of scripts/mutation-go-texts.go.",
		Generator:   "scripts/mutation-go-texts.go",
		Spec:        c.Spec,
	}
	for _, m := range c.Cases {
		var base []byte
		if m.DKC.Base != "" {
			base = must(os.ReadFile(filepath.Join(dir, "fixtures", m.DKC.Base)))
		}
		dkc := applyEdits(base, m.DKC.Edits)
		reg := must(profile.Default())
		if m.Registry == "empty" {
			reg = must(profile.NewRegistry())
		}
		var src source
		if m.Release != nil {
			src.release = &provider.Release{Round: m.Release.Round, Signature: must(hex.DecodeString(m.Release.Signature))}
			if m.Release.ChainHash != "" {
				src.release.ChainHash = must(hex.DecodeString(m.Release.ChainHash))
			}
		}
		now := must(time.Parse(time.RFC3339Nano, m.Now))
		o := capsule.OpenOptions{Registry: reg, Now: func() time.Time { return now }, Sink: discard{}}
		switch m.Source {
		case "supplied":
			o.Release = src
		case "network":
			o.Source = src
		default:
			panic(fmt.Sprintf("%s: unknown source %q", m.Name, m.Source))
		}
		if m.Extensions != nil {
			var k known
			for _, x := range m.Extensions {
				k = append(k, struct {
					id      string
					version uint64
					valid   []byte
				}{x.ID, x.Version, must(hex.DecodeString(x.ValidData))})
			}
			o.Extensions = k
		}
		if m.DKK != "" {
			o.AccessKey = must(accesskey.Decode(bytes.NewReader(must(hex.DecodeString(m.DKK)))))
		}
		for _, s := range m.Identities {
			o.Identities = append(o.Identities, must(age.ParseX25519Identity(s)))
		}
		_, err := capsule.Open(context.Background(), io.Discard, bytes.NewReader(dkc), o)
		text, code := "ok", "ok"
		if err != nil {
			text, code = err.Error(), datekeys.Code(err)
		}
		if code != m.Error {
			panic(fmt.Sprintf("%s: %s, the corpus says %s", m.Name, text, m.Error))
		}
		out.Cases = append(out.Cases, caseOut{m.Name, text})
	}
	e := json.NewEncoder(os.Stdout)
	e.SetEscapeHTML(false)
	e.SetIndent("", " ")
	if err := e.Encode(out); err != nil {
		panic(err)
	}
}