package chatflow

import (
	"context"
	"fmt"
	"strings"
	"time"

	"chat-agent-system/internal/coordinator"
	"chat-agent-system/internal/ctxmgr"
	"chat-agent-system/internal/maturity"
)

// Assembler adapts coordinator.ContextAssembler and ChatLog so prompt context
// only contains the authorized message set.
type Assembler struct {
	Inner *coordinator.ContextAssembler
	Log   ChatLog
}

func NewAssembler(inner *coordinator.ContextAssembler, log ChatLog) *Assembler {
	if inner == nil {
		inner = coordinator.NewContextAssembler()
	}
	return &Assembler{Inner: inner, Log: log}
}

func (a *Assembler) Assemble(ctx context.Context, p Principal, req AssembleRequest) (*coordinator.UserProjectContext, error) {
	if p.UserID <= 0 {
		return nil, ErrUnauthenticated
	}
	p.Action = ActionAssemble

	var userCtx *coordinator.UserProjectContext
	if a.Inner != nil && strings.TrimSpace(req.WorkDir) != "" {
		userCtx, _ = a.Inner.AssembleFromWorkspace(req.WorkDir, req.User)
	}
	if userCtx == nil {
		userCtx = &coordinator.UserProjectContext{
			SnapshotID:       fmt.Sprintf("ctx_%d", time.Now().UnixNano()),
			AssembledAt:      time.Now(),
			User:             req.User,
			WorkDir:          req.WorkDir,
			Project:          req.Fallback,
			BlackboardFacts:  make(map[string]string),
			AvailableActions: coordinator.ComputeAvailableActions(maturity.StageV01_Triage, req.User.ProjectRole),
		}
		if userCtx.Project.CurrentStage == "" {
			userCtx.Project.CurrentStage = maturity.StageV01_Triage
		}
		if userCtx.Project.CurrentWorkflow == "" {
			userCtx.Project.CurrentWorkflow = "intake"
		}
	}

	if a.Log == nil || strings.TrimSpace(req.SessionID) == "" {
		return userCtx, nil
	}
	restored, err := a.Log.Restore(ctx, p, req.SessionID)
	if err != nil {
		if err == ErrForbidden || err == ErrNotFound || err == ErrUnauthenticated {
			userCtx.RecentDialogue = nil
			userCtx.DialogueSummary = ""
			userCtx.RecalledMemories = nil
			userCtx.RecalledMemorySnippet = ""
			return userCtx, nil
		}
		return nil, err
	}
	if restored == nil {
		return userCtx, nil
	}
	upd := coordinator.ContextUpdate{
		ExpectedVersion:   userCtx.Version,
		BlackboardFill:    restored.Facts,
		SetRecentDialogue: true,
		RecentDialogue:    authorizedTurns(restored),
	}
	if restored.ProjectID > 0 {
		upd.ProjectIDIfEmpty = fmt.Sprintf("%d", restored.ProjectID)
	}
	_ = coordinator.ApplyContextUpdate(userCtx, upd)
	return userCtx, nil
}

func authorizedTurns(restored *ctxmgr.RestoredSessionContext) []coordinator.DialogueTurn {
	if restored == nil {
		return nil
	}
	turns := make([]coordinator.DialogueTurn, 0, len(restored.Messages))
	records := make([]ctxmgr.ChatMessageRecord, 0, len(restored.Messages))
	for _, m := range restored.Messages {
		if strings.TrimSpace(m.Content) == "" {
			continue
		}
		turns = append(turns, coordinator.DialogueTurn{Role: m.Role, Content: m.Content})
		records = append(records, m)
	}
	cfg := ctxmgr.DefaultWindowConfig()
	window, _, _ := ctxmgr.AssembleWindow(records, cfg)
	if len(window) > 0 {
		turns = turns[:0]
		for _, m := range window {
			if strings.TrimSpace(m.Content) == "" {
				continue
			}
			turns = append(turns, coordinator.DialogueTurn{Role: m.Role, Content: m.Content})
		}
	}
	return turns
}