// Package config is maven's daemon configuration.
//
// The daemon reads a single JSON file at startup (path from the -config flag,
// default ~/.config/maven/mavend.json). Everything a module needs is wired
// from this file: the store path, the unix socket path, the tick cadence,
// and per-sink configs (ntfy/telegram). Credentials live in the file (or a
// systemd credential that the file points at) — never in the binary.
//
// This package is pure data + a loader. It imports the sink config structs
// so the daemon wires each `Sink` from a single, typed config tree without
// re-declaring their shapes (the sink constructors own validation).
package config

import (
	"encoding/json"
	"errors"
	"fmt"
	"os"
	"path/filepath"
	"time"

	"github.com/kami/maven/internal/delivery/ntfysink"
	"github.com/kami/maven/internal/delivery/telegramsink"
)

// Config — the daemon's whole config tree. Loaded once at startup.
//
// Fields with omitempty are optional: a missing sink config = that channel
// not wired (the dispatcher's nil-sink path skips it silently, the same as a
// deliberately-unwired channel at scaffold time).
type Config struct {
	// DBPath — sqlite database path. Default applied by Load if empty.
	DBPath string `json:"db_path"`

	// SocketPath — the unix socket the IPC server listens on. Modules
	// connect here; the dir is created 0700, the socket chmod'd 0600 by
	// ipc.Listen. Default applied by Load if empty.
	SocketPath string `json:"socket_path"`

	// StateDir — base dir for db + socket if their paths aren't absolute.
	// Default applied by Load if empty (XDG-style: ~/.local/share/maven for
	// the db, /run/user/$UID/maven for the socket).
	StateDir string `json:"state_dir,omitempty"`

	// TickInterval — the proactive loop cadence. Default 60s. The loop is
	// "dumb + deterministic": most ticks evaluate a few predicates and die
	// for free; raising this saves nothing worth losing responsiveness over.
	TickInterval Duration `json:"tick_interval,omitempty"`

	// RepeatInterval — how often sev4 telegram sends re-fire until acked.
	// Default 5m. A disk-fire alarm that repeats every tick (60s) is spam;
	// one that repeats never is silent. The default tilts toward "loud."
	RepeatInterval Duration `json:"repeat_interval,omitempty"`

	// AutotuneInterval — how often the feedback auto-tuner runs: reads
	// store.RecentOutcomes for each rule, calls loop.TuneCooldown, writes the
	// tuned cooldown back as a `facts (kind=config, source=feedback)` row
	// if it changed. Default 10m — slow enough to be cheap + not write every
	// tick (append-only facts churn), fast enough that a weird-afternoon
	// pattern shows up inside a day. 0 ⇒ autotune disabled (the gatherer
	// falls back to the rule's static Base, matching pre-autotune behavior).
	AutotuneInterval Duration `json:"autotune_interval,omitempty"`

	// Ntfy — the ntfy push sink config. nil ⇒ ntfy channel not wired.
	// sev3 (ops soft) away + sev4 (ops hard) present + reminders away all
	// route here; not wiring ntfy means those routes drop silently.
	Ntfy *ntfysink.Config `json:"ntfy,omitempty"`

	// Telegram — the telegram push sink config. nil ⇒ telegram channel
	// not wired. sev4 away routes here with repeat-til-ack; not wiring
	// telegram means sev4-away alarms silently drop (a disk-fire alarm at
	// 2am that no one sees — wire it).
	Telegram *telegramsink.Config `json:"telegram,omitempty"`

	// Phraser — the LLM-backed phraser config. nil ⇒ the daemon uses the
	// template-based Stub (deterministic, no model required — good for CI).
	// When configured, the daemon spawns llama-server as a subprocess and
	// calls its /v1/chat/completions endpoint to phrase nudges and reminders.
	Phraser *PhraserConfig `json:"phraser,omitempty"`

	// Voice — the client↔core surface + the stt/tts modules the daemon
	// wires. nil ⇒ the daemon doesn't wire voice: the TCP listener stays
	// down, the dispatcher's Voice slot stays nil (the routing table's
	// ChannelVoice selections drop silently — same as pre-voice behaviour).
	// To enable: voice.enabled = true AND voice.bind = an address inside
	// the wg tunnel; the daemon binds the TCP listener there.
	Voice *VoiceConfig `json:"voice,omitempty"`
}

// VoiceConfig — the client↔core TCP surface + the stt/tts worker-module
// seams.
//
// Enabled gates wiring; Bind is the TCP address (inside the wg tunnel in
// production; "127.0.0.1:9100" for the local smoke). Lang is the default
// language hint passed to both stt and tts (per-call overrides later).
//
// Stt and Tts are the worker-module seams. nil Stt ⇒ daemon wires the
// in-process stt.Stub (the "no models on disk" floor — the loop is
// exercisable end-to-end with a deterministic no-model transcriber).
// non-nil Stt with Socket ⇒ daemon wires stt.Remote dialing that unix
// socket (cmd/mavsttd serves the other end; production swaps in a
// faster-whisper handler in cmd/mavsttd, no daemon or stt-package
// change). Tts mirrors for tts.Remote + cmd/mavttsd.
//
// Embedder configures the router's sentence embedder. When all three
// paths are set, the daemon constructs an ONNX multilingual embedder
// (in-process); when nil, it falls back to the floor HashEmbedder stub
// (deterministic, no model files required — good for CI and smoke).
//
// The daemon refuses to start if Voice.Enabled but Bind is empty — the
// bind is the one operational config the surface can't default (127.0.0.1
// is too relaxed for production, a wg-tunnel address is the user's);
// surfacing the gap explicitly beats an idle listener the user thinks is
// wired but isn't reachable.
type VoiceConfig struct {
	Enabled  bool            `json:"enabled,omitempty"`
	Bind     string          `json:"bind,omitempty"`
	Lang     string          `json:"lang,omitempty"`
	Stt      *WorkerConfig   `json:"stt,omitempty"`
	Tts      *TtsConfig      `json:"tts,omitempty"`
	Embedder *EmbedderConfig `json:"embedder,omitempty"`

	// Tools — the enabled act allowlist. Each is a spoken verb → argv the
	// executor runs (args from the utterance appended). Editing this set is the
	// human-only "enable" act (per spec); maven can't add to it from a request.
	// Empty ⇒ every act is refused (nothing enabled).
	Tools []ToolConfig `json:"tools,omitempty"`

	// ToolTimeout bounds each tool invocation. Zero ⇒ executor default (30s).
	ToolTimeout Duration `json:"tool_timeout,omitempty"`
}

// ToolConfig — one enabled tool. Name is the spoken verb ("restart"); Cmd is
// the fixed argv prefix (["systemctl","restart"]); Destructive marks acts that
// must not fire from the voice path (they need a confirm on an authed surface).
type ToolConfig struct {
	Name        string   `json:"name"`
	Cmd         []string `json:"cmd"`
	Destructive bool     `json:"destructive,omitempty"`
}

// PhraserConfig — the LLM-backed phraser seam. The daemon spawns llama-server
// as a managed subprocess and sends chat-completion requests to phrase nudge
// and reminder messages. nil ⇒ the template-based Stub is used instead.
//
// ModelPath is the only required field. The rest have sensible defaults:
//   - BinPath defaults to "llama-server" (found via PATH at spawn time).
//   - Listen defaults to "127.0.0.1:0" (random port, read from stderr).
//   - NGpuLayers defaults to -1 (max, uses all available GPU layers).
//   - NCtx defaults to 2048.
//   - Timeout defaults to 30s per request.
type PhraserConfig struct {
	ModelPath  string `json:"model_path"`
	BinPath    string `json:"bin_path,omitempty"`
	Listen     string `json:"listen,omitempty"`
	NGpuLayers int    `json:"n_gpu_layers,omitempty"`
	NCtx       int    `json:"n_ctx,omitempty"`
	Timeout    Duration `json:"timeout,omitempty"`
}

// EmbedderConfig — paths for the ONNX multilingual embedder. The daemon
// constructs an in-process ONNX embedder when all three paths are non-empty;
// the router's classifier then uses real sentence embeddings instead of the
// floor HashEmbedder stub. Model_path is the ONNX model file, tokenizer_path
// is tokenizer.json (Unigram), lib_path is the ONNX Runtime shared library.
type EmbedderConfig struct {
	ModelPath    string `json:"model_path,omitempty"`
	TokenizerPath string `json:"tokenizer_path,omitempty"`
	LibPath      string `json:"lib_path,omitempty"`
}

// WorkerConfig — a unix-socket worker module connection. Used by Stt and
// (via TtsConfig embedding the same fields) by Tts. Socket is the unix
// socket path the worker module listens on (e.g.
// /run/user/$UID/maven/stt.sock). Lang overrides the surface default for
// this module when the user wants different langs for stt vs tts (rare).
type WorkerConfig struct {
	Socket string `json:"socket,omitempty"`
	Lang   string `json:"lang,omitempty"`
}

// TtsConfig — the tts worker module connection + tts-specific Voice field
// (a named voice when the worker supports multiple; "" ⇒ the worker's
// configured default).
type TtsConfig struct {
	Socket string `json:"socket,omitempty"`
	Lang   string `json:"lang,omitempty"`
	Voice  string `json:"voice,omitempty"`
}

// Duration — a time.Duration that round-trips through JSON as a string
// ("60s", "5m", "1h30m"). Plain time.Duration marshals as a nanosecond int,
// which is unreadable in a config file; this wrapper uses ParseDuration.
type Duration time.Duration

func (d Duration) MarshalJSON() ([]byte, error) {
	return json.Marshal(time.Duration(d).String())
}

func (d *Duration) UnmarshalJSON(b []byte) error {
	var s string
	if err := json.Unmarshal(b, &s); err != nil {
		return err
	}
	v, err := time.ParseDuration(s)
	if err != nil {
		return fmt.Errorf("config: bad duration %q: %w", s, err)
	}
	*d = Duration(v)
	return nil
}

// Defaults applied when the corresponding field is empty/zero.
const (
	DefaultTickInterval     = 60 * time.Second
	DefaultRepeatInterval   = 5 * time.Minute
	DefaultAutotuneInterval = 10 * time.Minute
)

// Load reads the JSON config at path and applies defaults. A missing file is
// an error — the daemon refuses to start without an explicit config (the
// default-less state is too permissive: empty db path, no sinks, an idle
// loop that silently does nothing, etc. — better to surface the gap than to
// run an idle daemon the user thinks is wired).
func Load(path string) (*Config, error) {
	b, err := os.ReadFile(path)
	if err != nil {
		return nil, fmt.Errorf("config: read %s: %w", path, err)
	}
	var c Config
	if err := json.Unmarshal(b, &c); err != nil {
		return nil, fmt.Errorf("config: parse %s: %w", path, err)
	}
	c.applyDefaults()
	if err := c.validate(); err != nil {
		return nil, fmt.Errorf("config: %s: %w", path, err)
	}
	return &c, nil
}

func (c *Config) applyDefaults() {
	if c.TickInterval == 0 {
		c.TickInterval = Duration(DefaultTickInterval)
	}
	if c.RepeatInterval == 0 {
		c.RepeatInterval = Duration(DefaultRepeatInterval)
	}
	if c.AutotuneInterval == 0 {
		c.AutotuneInterval = Duration(DefaultAutotuneInterval)
	}
	if c.DBPath == "" {
		c.DBPath = filepath.Join(defaultDataDir(), "maven.db")
	}
	if c.SocketPath == "" {
		c.SocketPath = filepath.Join(defaultRuntimeDir(), "mavend.sock")
	}
}

func (c *Config) validate() error {
	if c.Phraser != nil {
		if c.Phraser.ModelPath == "" {
			return errors.New("phraser.model_path is required")
		}
	}
	if c.Voice != nil && c.Voice.Enabled {
		if c.Voice.Bind == "" {
			return errors.New("voice.enabled set but voice.bind is empty — refusing to start a voice surface with no bind address")
		}
		if c.Voice.Embedder != nil {
			partial := c.Voice.Embedder.ModelPath == "" || c.Voice.Embedder.TokenizerPath == "" || c.Voice.Embedder.LibPath == ""
			if partial {
				return errors.New("voice.embedder: all three of model_path, tokenizer_path, lib_path must be set, or remove embedder to use the floor stub")
			}
		}
	}
	return nil
}

func defaultDataDir() string {
	if x := os.Getenv("XDG_DATA_HOME"); x != "" {
		return filepath.Join(x, "maven")
	}
	home, err := os.UserHomeDir()
	if err != nil || home == "" {
		return filepath.Join(os.TempDir(), "maven")
	}
	return filepath.Join(home, ".local", "share", "maven")
}

func defaultRuntimeDir() string {
	if x := os.Getenv("XDG_RUNTIME_DIR"); x != "" {
		return filepath.Join(x, "maven")
	}
	// /run/user/$UID is the typical answer; without XDG_RUNTIME_DIR, fall back
	// to the data dir (still works; just not tmpfs-clearance-on-reboot clean).
	return filepath.Join(defaultDataDir())
}