// Package loader loads persona definitions from YAML files using gopkg.in/yaml.v3.
// A persona is the self-awareness/identity bound to a character and, per
// DevDocs/design/01, it also carries the emotion state-machine parameters, the
// affection curve, and a per-persona memory namespace (memory isolation).
package loader

import (
	"errors"
	"fmt"

	"git.yeij.top/AskaEth/Cyrene_v2/internal/persona/emotion"
)

// Default affection bounds and step, applied when a persona defines no
// affection curve.
const (
	defaultAffectionMin   = 0
	defaultAffectionMax   = 100
	defaultAffectionInit  = 50
	defaultAffectionDelta = 5
)

// Thinking-move values accepted by ThinkingParams.Mode (design/01 §2.1). The
// empty string is equivalent to ThinkingModeDefault.
const (
	// ThinkingModeDefault leaves the provider's own reasoning behavior alone.
	ThinkingModeDefault = "default"
	// ThinkingModeOn explicitly enables reasoning where the provider has a switch.
	ThinkingModeOn = "on"
	// ThinkingModeOff explicitly disables reasoning where the provider has a switch.
	ThinkingModeOff = "off"
)

// ErrInvalidThinking is wrapped by the thinking-config validation error so a
// caller can detect a bad `thinking` block (unknown mode, negative budget)
// instead of seeing it silently ignored.
var ErrInvalidThinking = errors.New("persona: invalid thinking config")

// defaultMemoryNS is the namespace prefix used when a persona omits a concrete
// memory namespace; the full namespace becomes prefix + "." + persona id.
const defaultMemoryNS = "persona"

// Identity is the persona's self-awareness: the 人设 (who she is, e.g. a
// character role) plus the system prompt that carries that identity at runtime.
type Identity struct {
	// Role is the 人设 — the characterization the persona assumes.
	Role string `yaml:"role"`
	// SystemPrompt is the identity block injected as the system prompt.
	SystemPrompt string `yaml:"systemPrompt"`
}

// EmotionParams configures the persona's emotion state machine and its per-
// persona memory isolation namespace. Transitions may be empty, in which case
// the emotion package installs its default transition table.
type EmotionParams struct {
	InitialState emotion.EmotionState                            `yaml:"initialState"`
	DecayRate    float64                                         `yaml:"decayRate"`
	Transitions  map[emotion.EmotionState][]emotion.EmotionState `yaml:"transitions"`
	// MemoryNamespace is the memory isolation namespace for this persona.
	MemoryNamespace string `yaml:"memoryNamespace"`
}

// AffectionParams defines this persona's affection curve bounds and the default
// step applied to an Adjust call that carries no delta.
type AffectionParams struct {
	Initial int `yaml:"initial"`
	Min     int `yaml:"min"`
	Max     int `yaml:"max"`
	Delta   int `yaml:"delta"`
}

// ThinkingParams is the persona's optional `thinking` section (design/01 §2.1).
// It describes presentation/resource knobs only — never an ability bound — and
// defaults are chosen so an absent section changes nothing. It is marshaled by
// the admin persona write path, so every field is omitempty: a persona that
// configures no thinking gets no `thinking:` key in its YAML.
type ThinkingParams struct {
	// BudgetTokens is the reasoning budget (Anthropic thinking.budget_tokens; the
	// official semantic is a target, not a hard cap). Zero = unset.
	BudgetTokens int `yaml:"budgetTokens,omitempty"`
	// Effort is the OpenAI-compatible reasoning strength (reasoning_effort). The
	// accepted values depend on the provider; the model layer validates them
	// against its per-provider whitelist (design/04 §3.2).
	Effort string `yaml:"effort,omitempty"`
	// ShowToUser says whether streamed thinking frames are pushed to the client.
	// It is a POINTER on purpose: a missing key means "keep the current behavior"
	// (thinking frames are shown), while an explicit false means "store it, but
	// do not push it". A plain bool would conflate "unset" with "off".
	ShowToUser *bool `yaml:"showToUser,omitempty"`
	// Mode is the explicit hard switch: default | on | off. Empty = default.
	Mode string `yaml:"mode,omitempty"`
}

// Enable maps Mode onto the model layer's tri-state switch: "on" → true, "off" →
// false, ""/"default" → nil (no explicit switch, leave it to the provider). The
// reasoning knobs the model layer consumes never include a null switch, so
// "default" cannot accidentally turn provider thinking on.
func (t ThinkingParams) Enable() *bool {
	switch t.Mode {
	case ThinkingModeOn:
		v := true
		return &v
	case ThinkingModeOff:
		v := false
		return &v
	default:
		return nil
	}
}

// Persona is a loaded persona definition. It describes who a character is (the
// identity, personality, speech style, catchphrase, background, values) and
// never restricts what that character can do.
// PersonaVisual carries the persona-owned visual assets (per-role icon/avatar
// and optional chat background). Each persona configures its OWN visuals; the UI
// renders the current persona's resources, so one role never inherits another's.
type PersonaVisual struct {
	// Avatar is the persona's avatar image path (e.g. /images/Cyrene_Avatar/...).
	Avatar string `yaml:"avatar,omitempty"`
	// ChatBackground optionally sets the persona's chat backdrop, per orientation.
	ChatBackground ChatBackground `yaml:"chatBackground,omitempty"`
}

// ChatBackground holds per-orientation chat wallpaper paths (landscape/portrait).
type ChatBackground struct {
	Landscape string `yaml:"landscape,omitempty"`
	Portrait  string `yaml:"portrait,omitempty"`
}

// DefaultAvatar is the neutral fallback avatar shown when a persona has no
// avatar configured (so a role never silently borrows another persona's view).
const DefaultAvatar = "/images/User_Avatar/Default_Avatar.png"

type Persona struct {
	ID           string          `yaml:"id"`
	Name         string          `yaml:"name"`
	CharacterRef string          `yaml:"characterRef"`
	Identity     Identity        `yaml:"identity"`
	Personality  string          `yaml:"personality"`
	SpeechStyle  string          `yaml:"speechStyle"`
	Catchphrase  string          `yaml:"catchphrase"`
	Background   string          `yaml:"background"`
	Values       []string        `yaml:"values"`
	Emotion      EmotionParams   `yaml:"emotion"`
	Affection    AffectionParams `yaml:"affection"`
	// Thinking is the optional reasoning/presentation config (design/01 §2.1);
	// omitted when the persona configures none, so no existing YAML gains noise.
	Thinking ThinkingParams `yaml:"thinking,omitempty"`
	// Awakening 是该人格可选的唤醒档位覆盖（design/14 §3，裁决 14.4.3）。
	// nil = 角色档案里没写该块 = 没有该档位：不补默认值，由决策层走全局默认。
	Awakening *AwakeningParams `yaml:"awakening,omitempty"`
	Visual    PersonaVisual    `yaml:"visual,omitempty"`
	// TriggerWords are the role-name words that, when a public-platform group
	// message mentions one, route the message into the participation PROBING
	// stage even without a direct @ (design/18 §2 触发②). Each persona defines its
	// own reminder words; they never imply identity (that stays structural).
	TriggerWords []string `yaml:"triggerWords,omitempty"`
}

// EmotionConfig converts this persona's own fields into the params consumed by
// the emotion machine constructor.
func (p *Persona) EmotionConfig() emotion.Params {
	return emotion.Params{
		InitialState: p.Emotion.InitialState,
		DecayRate:    p.Emotion.DecayRate,
		Transitions:  p.Emotion.Transitions,
	}
}

// MemoryNamespace returns the effective memory isolation namespace for this
// persona — the configured one, or a derived default of "persona.<id>" when none
// is set. The derived default guarantees per-persona isolation.
func (p *Persona) MemoryNamespace() string {
	if p.Emotion.MemoryNamespace != "" {
		return p.Emotion.MemoryNamespace
	}
	return defaultMemoryNS + "." + p.ID
}

// NewMachine builds the persona's emotion state machine from its config.
func (p *Persona) NewMachine() (*emotion.Machine, error) {
	return emotion.NewMachine(p.EmotionConfig())
}

// NewAffection builds the persona's affection tracker from its curve config,
// applying default bounds when no curve was defined.
func (p *Persona) NewAffection() (*emotion.Affection, error) {
	params := p.Affection
	if params.Min == 0 && params.Max == 0 && params.Initial == 0 && params.Delta == 0 {
		params = AffectionParams{
			Initial: defaultAffectionInit,
			Min:     defaultAffectionMin,
			Max:     defaultAffectionMax,
			Delta:   defaultAffectionDelta,
		}
	}
	return emotion.NewAffection(params.Initial, params.Min, params.Max)
}

// AffectionStep returns the per-turn affection magnitude of this persona's
// 好感度曲线 (design/01 §2) — the configured `affection.delta`, or the loader
// default when the persona declares no curve. It is the magnitude applied once
// per emotional turn; the sign comes from the turn's signal.
func (p *Persona) AffectionStep() int {
	if p.Affection.Delta != 0 {
		return p.Affection.Delta
	}
	return defaultAffectionDelta
}

// ValidateThinking checks the optional `thinking` section and returns a
// %w-wrapped ErrInvalidThinking error for an unrecognized mode or a negative
// budget, so a bad value is reported instead of silently ignored.
func (p *Persona) ValidateThinking() error {
	switch p.Thinking.Mode {
	case "", ThinkingModeDefault, ThinkingModeOn, ThinkingModeOff:
	default:
		return fmt.Errorf("%w: mode %q (want %s|%s|%s)",
			ErrInvalidThinking, p.Thinking.Mode, ThinkingModeDefault, ThinkingModeOn, ThinkingModeOff)
	}
	if p.Thinking.BudgetTokens < 0 {
		return fmt.Errorf("%w: budgetTokens %d must not be negative", ErrInvalidThinking, p.Thinking.BudgetTokens)
	}
	return nil
}