package testkit

import (
	"encoding/json"
	"os"
	"path/filepath"
	"regexp"
)

// FixtureStanza is the visible part of an age stanza in a fixture.
type FixtureStanza struct {
	Type string   `json:"type"`
	Args []string `json:"args"`
}

// FixtureRelease is the release a fixture opens with.
type FixtureRelease struct {
	Round     uint64 `json:"round"`
	Signature string `json:"signature"`
}

// FixtureStage is the expected result of one step of spec §63.
type FixtureStage struct {
	Step  int    `json:"step"`
	Name  string `json:"name"`
	OK    bool   `json:"ok"`
	Error string `json:"error,omitempty"`
}

// DKCFixture holds the expected values of an official .dkc fixture (spec §67).
type DKCFixture struct {
	Description string `json:"description"`
	Spec        string `json:"spec"`
	// Format is the capsule format, the VERSION of the PRELUDE (spec §22).
	Format         int             `json:"format"`
	File           string          `json:"file"`
	SHA256         string          `json:"sha256"`
	Release        FixtureRelease  `json:"release"`
	Prelude        string          `json:"prelude"`
	PublicHeader   string          `json:"public_header"`
	DateKey        string          `json:"datekey"`
	CapsuleID      string          `json:"capsule_id"`
	AccessPolicy   string          `json:"access_policy"`
	Structure      string          `json:"structure"`
	UnlockAt       string          `json:"unlock_at"`
	HeaderBinding  string          `json:"header_binding"`
	OuterStanzas   []FixtureStanza `json:"outer_stanzas"`
	PayloadStanzas []FixtureStanza `json:"payload_stanzas"`
	InnerStanzas   []FixtureStanza `json:"inner_stanzas,omitempty"`
	// AccessKeyStanza and IdentityStanzas are, in a format 2 time_and_key
	// fixture, the index in InnerStanzas of the stanza each credential
	// opens: the .dkk, and each identity of Identities in order. The stanzas
	// no credential opens are dummies. Official vectors are the only place
	// where this is recorded (spec §39, §67).
	AccessKeyStanza *int     `json:"access_key_stanza,omitempty"`
	IdentityStanzas []int    `json:"identity_stanzas,omitempty"`
	AccessKeyFile   string   `json:"access_key_file,omitempty"`
	Identities      []string `json:"identities,omitempty"`
	ControlCBOR     string   `json:"control_cbor"`
	PayloadIdentity string   `json:"payload_identity"`
	// PayloadLength is L, the length of the content: the plaintext the
	// reader delivers in formats 1 and 2, and BODY in format 3, whose files
	// Files describes. In formats 2 and 3 the plaintext of PAYLOAD_AGE is
	// PaddedLength bytes, P = rule(L), the rule being Padding (spec §29.1,
	// §29.2). PlaintextFile holds those L bytes.
	PayloadLength    uint64       `json:"payload_length"`
	Padding          int          `json:"padding,omitempty"`
	PaddedLength     uint64       `json:"padded_length,omitempty"`
	PlaintextFile    string       `json:"plaintext_file"`
	PlaintextSHA256  string       `json:"plaintext_sha256"`
	HeaderExtensions []FixtureExt `json:"header_extensions,omitempty"`
	ControlExt       []FixtureExt `json:"control_extensions,omitempty"`
	// The fields of format 3 (spec §29.2 to §29.7): the size of the security
	// area, SECURITY_CBOR and HEAD_CBOR, the salt, the comment and the
	// declared author, the extensions of the head, the offset of CONTENT in
	// BODY, 12 + AREA_LEN + HEAD_LEN, each file, and the verdicts.
	AreaLen        uint32           `json:"area_len,omitempty"`
	Security       string           `json:"security_cbor,omitempty"`
	Head           string           `json:"head_cbor,omitempty"`
	Salt           string           `json:"salt,omitempty"`
	Comment        string           `json:"comment,omitempty"`
	Author         string           `json:"declared_author,omitempty"`
	HeadExtensions []FixtureExt     `json:"head_extensions,omitempty"`
	ContentOffset  uint64           `json:"content_offset,omitempty"`
	Files          []FixtureFile    `json:"files,omitempty"`
	Verdicts       *FixtureVerdicts `json:"verdicts,omitempty"`
	// Signature is, in a fixture signed with alg 1, what a second
	// implementation needs to check the signature and to make it again
	// (spec v0.11, §29.8, §29.9).
	Signature *FixtureSignature `json:"signature,omitempty"`
	Stages    []FixtureStage    `json:"stages"`
}

// FixtureFile is a file of a format 3 fixture: its entry of the head. Its
// bytes are those of BODY from ContentOffset + Start to ContentOffset + End.
type FixtureFile struct {
	Path   string  `json:"path"`
	Size   uint64  `json:"size"`
	Start  uint64  `json:"start"`
	End    uint64  `json:"end"`
	SHA256 string  `json:"sha256"`
	MTime  *uint64 `json:"mtime,omitempty"`
}

// FixtureVerdicts are the verdicts of the security area of a format 3
// fixture, and the lines that show them (spec §29.7).
type FixtureVerdicts struct {
	Signature string   `json:"signature"`
	Seal      string   `json:"seal"`
	Lines     []string `json:"lines"`
	// AuthorKey is the dkauthor1… key of a valid signature (F3, F4).
	AuthorKey string `json:"author_key,omitempty"`
}

// FixtureSignature describes the signature of alg 1 of a format 3 fixture.
// SecretSeed is the 32-byte seed of a test key made for it: Ed25519 is
// deterministic, so signing AuthorMessage with it gives SignatureValue
// again. ControlCommit, HeadDigest and SignersDigest are the commitments of
// spec §29.8, in hexadecimal; AuthorMessage is the ASCII text that is
// signed, and AuthorCode its code. SecurityKey2 is the exact content of key
// 2 of SECURITY_CBOR, in hexadecimal.
type FixtureSignature struct {
	Alg            int    `json:"alg"`
	SecretSeed     string `json:"secret_seed"`
	AuthorKey      string `json:"author_key"`
	ControlCommit  string `json:"control_commit"`
	HeadDigest     string `json:"head_digest"`
	SignersDigest  string `json:"signers_digest"`
	AuthorMessage  string `json:"author_message"`
	AuthorCode     string `json:"author_code"`
	SignatureValue string `json:"signature"`
	SecurityKey2   string `json:"security_key_2"`
}

// FixtureExt is an extension in a fixture.
type FixtureExt struct {
	Critical bool   `json:"critical"`
	ID       string `json:"id"`
	Version  uint64 `json:"version"`
	Data     string `json:"data,omitempty"` // hex of the exact data bytes; absent without data
}

// DKKFixture holds the expected values of an official .dkk fixture (spec §68).
type DKKFixture struct {
	Description    string         `json:"description"`
	Spec           string         `json:"spec"`
	File           string         `json:"file"`
	SHA256         string         `json:"sha256"`
	CredentialID   string         `json:"credential_id"`
	CapsuleID      string         `json:"capsule_id"`
	AccessType     string         `json:"access_type"`
	Material       string         `json:"access_material"`
	CapsuleDigest  string         `json:"capsule_digest,omitempty"`
	Extensions     []FixtureExt   `json:"extensions,omitempty"`
	Capsule        string         `json:"capsule"`
	ExpectedResult string         `json:"expected_result"`
	Stages         []FixtureStage `json:"stages,omitempty"`
}

// ReadJSON decodes a JSON file.
func ReadJSON(path string, v any) error {
	b, err := os.ReadFile(path)
	if err != nil {
		return err
	}
	return json.Unmarshal(b, v)
}

// WriteJSON writes v as indented JSON with a trailing newline.
func WriteJSON(path string, v any) error {
	b, err := json.MarshalIndent(v, "", "  ")
	if err != nil {
		return err
	}
	return writeFile(path, append(b, '\n'))
}

// editPattern is an Edit as json.MarshalIndent spreads it over five lines.
var editPattern = regexp.MustCompile(`\[\n\s*(\d+),\n\s*(\d+),\n\s*("[0-9a-f]*")\n\s*\]`)

// WriteJSONEdits is WriteJSON with every Edit, [at, delete, "hex"], on one
// line.
func WriteJSONEdits(path string, v any) error {
	b, err := json.MarshalIndent(v, "", "  ")
	if err != nil {
		return err
	}
	return writeFile(path, append(editPattern.ReplaceAll(b, []byte("[$1, $2, $3]")), '\n'))
}

func writeFile(path string, b []byte) error {
	if err := os.MkdirAll(filepath.Dir(path), 0o755); err != nil {
		return err
	}
	return os.WriteFile(path, b, 0o644)
}