// Package config loads, defaults, and validates the Cyrene v2 configuration
// from environment variables and an optional .env file (development only).
//
// Every setting is sourced from an environment variable (no hard-coded values
// in code). Nested groups map to struct fields tagged with `env:"NAME"`.
// Missing required values cause Load/MustLoad to return an error so startup
// can fail fast.
package config

import (
	"fmt"
	"reflect"
	"strings"
)

// Config is the root configuration tree.
type Config struct {
	Env            string   `env:"ENV" default:"development"`
	LogLevel       string   `env:"LOG_LEVEL" default:"debug"`
	Timezone       string   `env:"TZ" default:"Asia/Shanghai"`
	DataDir        string   `env:"DATA_DIR" default:"./data"`
	AllowedOrigins []string `env:"ALLOWED_ORIGINS" default:"http://localhost:5173,http://localhost:3000"`

	Server      ServerConfig
	Auth        AuthConfig
	DB          DBConfig
	LLM         LLMConfig
	Embedding   EmbeddingConfig
	IoT         IoTConfig
	Voice       VoiceConfig
	Background  BackgroundConfig
	WSHub       WSHubConfig
	ExecSandbox ExecSandbox
	MCP         MCPConfig
	Capacity    CapacityConfig
}

// ServerConfig holds the single gateway listener settings.
type ServerConfig struct {
	Host string `env:"HOST" default:"0.0.0.0"`
	Port int    `env:"PORT" default:"8080"`
}

// AuthConfig holds authentication and admin credential settings.
type AuthConfig struct {
	JWTSecret           string `env:"JWT_SECRET" validate:"required,min=32"`
	AdminUser           string `env:"ADMIN_USERNAME" default:"admin"`
	AdminPass           string `env:"ADMIN_PASSWORD" default:"admin12345"`
	RegistrationEnabled bool   `env:"REGISTRATION_ENABLED" default:"true"`
}

// DBConfig holds database connection settings. SQLite is the default; PGURL is
// the optional PostgreSQL+pgvector enhancement.
type DBConfig struct {
	SQLitePath string `env:"DB_SQLITE_PATH" default:"./data/cyrene.db"`
	PGURL      string `env:"DB_PG_URL"`
}

// LLMConfig holds the multi-supplier LLM adapter settings. Provider selects the
// wire protocol; every provider has its own independent base/key/model/fallback
// so multiple vendors can coexist.
type LLMConfig struct {
	// Provider declares which protocol to use: "openai" (OpenAI-compatible
	// /chat/completions) or "anthropic" (Anthropic Messages /v1/messages).
	Provider string `env:"LLM_PROVIDER" default:"openai"`

	// OpenAI-compatible provider (default). Kept flat for backward compatibility
	// with the historic LLM_BASE_URL/API_KEY/MODEL/FALLBACK_MODEL env names.
	BaseURL  string `env:"LLM_BASE_URL"`
	APIKey   string `env:"LLM_API_KEY"`
	Model    string `env:"LLM_MODEL"`
	Fallback string `env:"LLM_FALLBACK_MODEL"`

	// VisionModel is the dedicated model used for image/vision requests. When
	// set, the model router routes image content to it (see model.Router.WithVisionModel).
	VisionModel string `env:"LLM_VISION_MODEL"`

	// Anthropic native provider, used when Provider=anthropic. Independent
	// config block so each vendor is a self-contained config.
	AnthropicBaseURL  string `env:"ANTHROPIC_BASE_URL"`
	AnthropicAPIKey   string `env:"ANTHROPIC_API_KEY"`
	AnthropicModel    string `env:"ANTHROPIC_MODEL"`
	AnthropicFallback string `env:"ANTHROPIC_FALLBACK_MODEL"`
}

// EmbeddingConfig holds the optional semantic embedding API settings. When
// unset, the runtime falls back to built-in n-gram/FTS vectors.
type EmbeddingConfig struct {
	APIURL string `env:"EMBEDDING_API_URL"`
	APIKey string `env:"EMBEDDING_API_KEY"`
	Model  string `env:"EMBEDDING_MODEL"`
}

// IoTConfig selects the IoT device provider.
type IoTConfig struct {
	Provider string `env:"IOT_PROVIDER" default:"mock"`
}

// VoiceConfig holds TTS/STT provider settings.
type VoiceConfig struct {
	TTSProvider     string `env:"TTS_PROVIDER" default:"edge-tts"`
	STTProvider     string `env:"STT_PROVIDER" default:"dashscope"`
	DashscopeAPIKey string `env:"DASHSCOPE_API_KEY"`
}

// BackgroundConfig holds the autonomous thinking settings.
type BackgroundConfig struct {
	Enabled        bool `env:"ENABLE_BACKGROUND_THINKING" default:"true"`
	IntervalSec    int  `env:"THINK_INTERVAL_SEC" default:"300"`
	SilenceTimeout int  `env:"THINK_SILENCE_TIMEOUT_SEC" default:"120"`
}

// WSHubConfig holds the WebSocket hub limits.
type WSHubConfig struct {
	MaxConnections     int `env:"WS_MAX_CONNECTIONS" default:"1000"`
	SessionIdleTimeout int `env:"SESSION_IDLE_TIMEOUT_MIN" default:"30"`
}

// MCPConfig holds Model Context Protocol server settings. The reflection-based
// loader only supports scalars and []string, so servers are supplied as a JSON
// array string (ServersJSON, env MCP_SERVERS_JSON) and parsed at startup by the
// MCP wiring (cmd/cyrene/mcp.go).
type MCPConfig struct {
	ServersJSON string `env:"MCP_SERVERS_JSON"`
}

// CapacityConfig configures the awakened-capacity decision layer
// (DevDocs/design/14-唤醒式能力渐进.md §4). It is opt-in: the loop exposes every
// tool until Enabled is true.
type CapacityConfig struct {
	// Enabled turns on the capacity decider. When false the loop advertises every
	// registered tool (pre-existing behavior). Note: it is wired at the loop
	// periphery, not back-end (Invoke stays unblocked).
	Enabled bool `env:"CAPACITY_ENABLED" default:"false"`
	// MinConfidence is the wake threshold below which the state is forced toward
	// the persona default (设计 §2.3 默认保守). Zero selects the code default 0.6.
	MinConfidence float64 `env:"CAPACITY_MIN_CONFIDENCE" default:"0.6"`
	// ToolSetsJSON, when non-empty, is a JSON map of state→[]tool name, e.g.
	// {"quiet":["terminal","file"],"awake":["terminal","file","web-search"],
	// "full":null}. A missing state selects the built-in default set; null ("full")
	// means unrestricted. Parsed by the capacity wiring at startup (the
	// reflection-based loader only supports scalars and []string), matching the
	// MCP config pattern.
	ToolSetsJSON string `env:"CAPACITY_TOOL_SETS"`
}

// MCPServer describes a single MCP server: a stdio subprocess (Command/Args) or
// an SSE endpoint (URL). Enabled gates activation at startup.
type MCPServer struct {
	Name    string   `json:"name"`
	Command string   `json:"command"`
	Args    []string `json:"args"`
	URL     string   `json:"url"`
	Enabled bool     `json:"enabled"`
}

// Load reads configuration, merging an optional .env file (development only)
// with process environment variables. Process environment variables always take
// precedence over .env values, which take precedence over code defaults.
//
// Passing an empty envPath skips .env entirely. A missing .env file is not an
// error; only missing required values are.
func Load(envPath string) (*Config, error) {
	fromEnv := map[string]string{}
	if envPath != "" {
		m, err := parseDotEnv(envPath)
		if err != nil {
			return nil, fmt.Errorf("config: read %s: %w", envPath, err)
		}
		fromEnv = m
	}

	cfg := &Config{}
	if err := decodeValue(reflect.ValueOf(cfg), fromEnv); err != nil {
		return nil, err
	}

	if errs := validateStruct(reflect.ValueOf(cfg).Elem()); len(errs) > 0 {
		parts := make([]string, 0, len(errs))
		for _, e := range errs {
			parts = append(parts, e.Error())
		}
		return nil, fmt.Errorf("config: validation failed: %s", strings.Join(parts, "; "))
	}

	return cfg, nil
}

// MustLoad is Load that panics on error. It is intended for startup, matching
// the "schema validation fails at boot" rule.
func MustLoad(envPath string) *Config {
	cfg, err := Load(envPath)
	if err != nil {
		panic(err)
	}
	return cfg
}