package channelbridge

import (
	"context"
	"strings"

	"git.yeij.top/AskaEth/Cyrene_v2/internal/channel/session"
	"git.yeij.top/AskaEth/Cyrene_v2/internal/runtime/history"
)

// This file owns which role an inbound IM turn speaks as (DevDocs/design/22 §2
// 裁决规则 + §7-3 + §7-4). Identity and permission stay structural — the actor
// metadata and the session's isolation boundary decide who may do what — while the
// role only scopes the prompt, the memory namespace, the emotion machine and the
// thinking budget.
//
// Precedence, top down (design/22 §2):
//  1. the session-level binding — for an owner private chat that is the main web
//     session the message is mirrored into, so the IM mirror answers with the same
//     role the Web client is talking to (design/22 §7-3);
//  2. the channel-level binding — the account's channels.json personaId, used when
//     the main session binds no role of its own (design/22 §2 方案 b);
//  3. the global default — expressed as "", which the loop resolves to its
//     configured default role.
//
// A restricted conversation (group chat or stranger, i.e. every isolated sess-xxx
// session) is deliberately excluded from 1 and 2: it is forced onto the default
// role (design/22 §7-4, the conservative choice), so a channel binding can never
// put a third party's conversation into a role's memory namespace.

// sessionPersonaReader is the optional narrower view of the history store used to
// read a session's bound role. *history.Store implements it; a bridge built
// without one (or with a store that predates design/22) simply resolves no session
// binding, which is the global default.
type sessionPersonaReader interface {
	SessionPersona(ctx context.Context, sessionID string) (string, error)
}

// resolvePersona returns the role id one inbound turn runs as. target says where
// the turn's conversation lives (the mirrored main session vs an isolated
// session), sess carries the structurally resolved isolation boundary and account
// is the receiving adapter's registration name (platform:confId) used for the
// channel-level lookup.
func (b *Bridge) resolvePersona(ctx context.Context, sess session.Session, target inboundTarget, account string) string {
	// design/22 §7-4: a group/stranger conversation never plays a bound role.
	if !target.private {
		return ""
	}
	// design/22 §7-3: an owner private chat mirrors into the main session, so it
	// answers as whatever role that session is bound to.
	if pid := b.mainSessionPersona(ctx); pid != "" {
		return pid
	}
	// design/22 §2 方案 b: the account's channel-level role, used only when the main
	// session binds no role of its own.
	return b.personaOfAdapter(account)
}

// mainSessionPersona returns the role bound to the main web session, or "" when
// the session inherits the global default. A missing reader or a read error also
// yields "": a chat must never be blocked by a metadata lookup, and the fallback is
// the pre-existing default role.
func (b *Bridge) mainSessionPersona(ctx context.Context) string {
	if b.history == nil {
		return ""
	}
	reader, ok := b.history.(sessionPersonaReader)
	if !ok {
		return ""
	}
	pid, err := reader.SessionPersona(ctx, history.MainSessionID)
	if err != nil {
		return ""
	}
	return strings.TrimSpace(pid)
}

// personaOfAdapter returns the cached channel-level role of one adapter
// registration name, or "" when none is bound (or none was resolved at connect
// time).
func (b *Bridge) personaOfAdapter(account string) string {
	b.mu.RLock()
	defer b.mu.RUnlock()
	return b.adapterPersona[account]
}

// rememberAdapterPersona resolves and caches the channel-level role of an adapter
// that just connected. Resolving at connect/reload time (rather than per message)
// keeps the inbound hot path free of config reads, while a panel save still takes
// effect immediately: it writes channels.json and calls Reload, which rebuilds and
// reconnects the platform's adapters, refreshing this cache.
func (b *Bridge) rememberAdapterPersona(account string) {
	if b.channelPersona == nil {
		return
	}
	platform, accountID, _ := strings.Cut(account, ":")
	pid := strings.TrimSpace(b.channelPersona(platform, accountID))
	b.mu.Lock()
	defer b.mu.Unlock()
	if pid == "" {
		delete(b.adapterPersona, account)
		return
	}
	b.adapterPersona[account] = pid
}

// forgetAdapterPersona drops an adapter's cached channel role when the account is
// removed (or renamed) by a reload, so a removed account can never keep answering
// as a role that is no longer configured.
func (b *Bridge) forgetAdapterPersona(account string) {
	b.mu.Lock()
	defer b.mu.Unlock()
	delete(b.adapterPersona, account)
}