package auth

import (
	"crypto/rand"
	"encoding/base64"
	"fmt"
	"log/slog"
	"sync"

	"git.yeij.top/AskaEth/Cyrene_v2/internal/config"
	"git.yeij.top/AskaEth/Cyrene_v2/internal/logger"
)

// APIKey manages a bounded, in-memory constant table of API keys, each bound to
// a Role so keys can be minted for admin/owner to reach administrative
// endpoints. Keys are generated with crypto/rand and stored by their string
// form. This suits the current single-binary milestone; production should
// persist keys (e.g. hashed) and support revocation.
type APIKey struct {
	mu   sync.RWMutex
	cfg  config.AuthConfig
	keys map[string]Role
	log  *slog.Logger
}

// NewAPIKey returns an empty key manager. cfg is accepted for constructor
// parity and future persistence settings; keys are runtime-generated.
func NewAPIKey(cfg config.AuthConfig) *APIKey {
	return &APIKey{
		cfg:  cfg,
		keys: make(map[string]Role),
		log:  logger.WithSource(slog.Default(), source),
	}
}

// Generate mints a new random key bound to role and stores it. Returns the
// plaintext key exactly once; it must not be logged.
func (k *APIKey) Generate(role Role) (string, error) {
	if !role.Valid() {
		return "", fmt.Errorf("%w: %q", ErrInvalidRole, role)
	}
	raw := make([]byte, keyLength)
	if _, err := rand.Read(raw); err != nil {
		return "", fmt.Errorf("auth: generate api key: %w", err)
	}
	key := base64.RawURLEncoding.EncodeToString(raw)

	k.mu.Lock()
	k.keys[key] = role
	k.mu.Unlock()
	return key, nil
}

// Verify reports whether key is a known, unrevoked API key.
func (k *APIKey) Verify(key string) bool {
	_, ok := k.Lookup(key)
	return ok
}

// Lookup returns the role bound to key.
func (k *APIKey) Lookup(key string) (Role, bool) {
	k.mu.RLock()
	defer k.mu.RUnlock()
	role, ok := k.keys[key]
	return role, ok
}

// Revoke removes key from the constant table.
func (k *APIKey) Revoke(key string) {
	k.mu.Lock()
	defer k.mu.Unlock()
	delete(k.keys, key)
}

// RevokeAll removes every currently registered API key and returns how many were
// removed. It is the administrative "revoke all" operation: after a call the
// table is empty, so no previously issued key can authenticate.
func (k *APIKey) RevokeAll() int {
	k.mu.Lock()
	defer k.mu.Unlock()
	n := len(k.keys)
	k.keys = make(map[string]Role)
	return n
}

// RevokeByMask removes every key whose masked identifier (the same derived id
// List returns) matches mask. It returns true when at least one key was revoked.
// The mask is lossy, so it is matched by recomputing it for each key; the table
// is small so a linear scan is fine. An empty or nil-returning call is a no-op.
func (k *APIKey) RevokeByMask(mask string) bool {
	if mask == "" {
		return false
	}
	k.mu.Lock()
	defer k.mu.Unlock()
	revoked := false
	for key := range k.keys {
		if maskKey(key) == mask {
			delete(k.keys, key)
			revoked = true
		}
	}
	return revoked
}

// List returns a summary of every currently registered API key for the admin
// panel. Key material is never returned; each identifier is masked so the panel
// can tell keys apart without exposing the secret. The in-memory store keeps no
// creation time, so CreatedAt is nil for every entry.
func (k *APIKey) List() []UserSummary {
	k.mu.RLock()
	defer k.mu.RUnlock()
	out := make([]UserSummary, 0, len(k.keys))
	for key, role := range k.keys {
		out = append(out, UserSummary{ID: maskKey(key), Username: "apikey", Role: role})
	}
	return out
}

// MaskKey renders a key's leading and trailing groups so the panel can identify
// an entry without revealing the secret. Short keys are fully hidden. It is the
// exported form of maskKey so callers (e.g. the admin issue handler) can return
// the same masked id the List page shows.
func MaskKey(key string) string { return maskKey(key) }

// maskKey renders a key's leading and trailing groups so the panel can identify
// an entry without revealing the secret. Short keys are fully hidden.
func maskKey(key string) string {
	if len(key) <= 8 {
		return "••••"
	}
	return key[:4] + "••••" + key[len(key)-4:]
}