package policy

import (
	"ai-operator/internal/dialogue/state"
	"ai-operator/internal/tools"
)

type Decision struct {
	Allowed            bool
	ToolName           string
	State              state.ConversationState
	ReasonCode         string
	UserMessageKey     string
	RequiredNextAction string
}

func AuthorizeTool(session state.ConversationSession, toolName string) Decision {
	d := Decision{ToolName: toolName, State: session.State, ReasonCode: "ok"}
	if !tools.Known(toolName) {
		return deny(d, "unknown_tool", "denied.not_ready", "none")
	}
	if session.State == state.StateEnded {
		return deny(d, "call_ended", "closing.started", "none")
	}
	if toolName == tools.SearchKnowledgeBase {
		return authorizeSearch(session, d)
	}
	allowed := allowedByState(session.State, toolName)
	if !allowed {
		return deny(d, "tool_not_allowed_in_state", "denied.not_ready", nextAction(session))
	}
	d.Allowed = true
	return d
}

func authorizeSearch(session state.ConversationSession, d Decision) Decision {
	if session.State == state.StateEnded || session.State == state.StateClosing || session.State == state.StateHandoff {
		return deny(d, "state_not_ready", "denied.not_ready", nextAction(session))
	}
	d.Allowed = true
	return d
}

func allowedByState(s state.ConversationState, tool string) bool {
	switch s {
	case state.StateLanguageSelection:
		return tool == tools.SearchKnowledgeBase || tool == tools.SetLanguage || tool == tools.SetRegion || tool == tools.RequestHumanHandoff || tool == tools.EndCall
	case state.StateRegionSelection:
		return tool == tools.SearchKnowledgeBase || tool == tools.SetRegion || tool == tools.SetLanguage || tool == tools.RequestHumanHandoff || tool == tools.EndCall
	case state.StateReadyToHelp:
		return tool == tools.SearchKnowledgeBase || tool == tools.SetLanguage || tool == tools.SetRegion || tool == tools.RequestHumanHandoff || tool == tools.EndCall
	case state.StateQuestionAnswering:
		return tool == tools.SearchKnowledgeBase || tool == tools.SetLanguage || tool == tools.SetRegion || tool == tools.RequestHumanHandoff || tool == tools.EndCall
	case state.StateHandoff:
		return tool == tools.RequestHumanHandoff || tool == tools.EndCall
	case state.StateClosing:
		return tool == tools.EndCall
	default:
		return false
	}
}

func deny(d Decision, reason, key, action string) Decision {
	d.Allowed = false
	d.ReasonCode = reason
	d.UserMessageKey = key
	d.RequiredNextAction = action
	return d
}

func nextAction(session state.ConversationSession) string {
	if session.Language != state.LanguageRU && session.Language != state.LanguageKK {
		return "infer_language"
	}
	if session.Region.Status != state.RegionSelected || session.Region.Code == "" {
		return "use_global_or_ask_region_if_needed"
	}
	return "wait_for_question"
}