// Copyright (c) 2026 Storm Dragon
// SPDX-License-Identifier: GPL-3.0-or-later
package app

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

	"git.stormux.org/storm/cthulhu/internal/atspi"
	"git.stormux.org/storm/cthulhu/internal/interaction"
	"git.stormux.org/storm/cthulhu/internal/tentaclewire"
)

type tentacleForms interface {
	Open(context.Context, interaction.Form) (<-chan internalUIResult, error)
	Notice(context.Context, tentaclewire.Presentation)
}

// One interaction per runtime. RPC requests remain short; human input and
// background transfer polling belong to this joined worker, never the input
// consumer. Session revocation cancels its form and retires all results.
func (runtime *tentacleRuntime) interact(ctx context.Context, command tentacleCommand, raw json.RawMessage) {
	select {
	case runtime.interactionSlots <- struct{}{}:
	default:
		runtime.report("A tentacle menu is already open.")
		return
	}
	defer func() { <-runtime.interactionSlots }()
	ctx, cancel := context.WithCancel(ctx)
	defer cancel()
	stop := context.AfterFunc(command.session.OutputContext(), cancel)
	defer stop()
	var temporaryFiles []string
	defer func() {
		for _, path := range temporaryFiles {
			os.RemoveAll(filepath.Dir(path))
		}
	}()
	for transitions := 0; transitions < 1024 && ctx.Err() == nil; transitions++ {
		value, err := tentaclewire.DecodeInteraction(raw)
		if err != nil || !runtime.validContinuation(command, value.Next) || !runtime.validContinuation(command, value.Poll) {
			command.session.Disable()
			runtime.output.RetireRevoked()
			runtime.report("A tentacle returned an invalid interaction and was disabled.")
			return
		}
		if runtime.output.gate.Locked() || runtime.output.gate.Suspended() {
			return
		}
		if value.Clipboard != nil {
			copyCtx, stopCopy := context.WithTimeout(ctx, time.Second)
			err = copyTentacleText(copyCtx, *value.Clipboard)
			stopCopy()
			if err != nil {
				value.Presentation = clipboardWriteFailure(value.Presentation)
			}
		}
		if value.Form == nil && value.Source == "" {
			runtime.output.Present(runtime.output.Capture(command.session.OutputContext()), value.Presentation, "tentacle/"+command.id)
			return
		}
		var submission tentaclewire.Submission
		if value.Form != nil {
			if runtime.forms == nil {
				runtime.callInteraction(ctx, command, value.Next, tentaclewire.Submission{Cancelled: true})
				runtime.report("Internal UI unavailable.")
				return
			}
			formCtx, closeForm := context.WithCancel(ctx)
			replies, openErr := runtime.forms.Open(formCtx, *value.Form)
			if openErr != nil {
				closeForm()
				runtime.callInteraction(ctx, command, value.Next, tentaclewire.Submission{Cancelled: true})
				runtime.report("Internal UI unavailable.")
				return
			}
			if value.Speech != "" || value.Braille != "" {
				runtime.forms.Notice(formCtx, value.Presentation)
			}
			reply, completed := runtime.waitTentacleForm(formCtx, command, value, replies)
			closeForm()
			if completed != nil {
				// Wait for EndInternalUI before announcing completion or copying text.
				select {
				case <-replies:
				case <-ctx.Done():
					return
				}
				raw = completed
				continue
			}
			submission = tentaclewire.Submission{Activated: reply.Activated, Values: reply.Values, Cancelled: reply.Cancelled || reply.Err != nil}
		} else {
			itemCtx, stopItem := context.WithTimeout(ctx, time.Second)
			var item tentaclewire.Item
			if value.Source == "focus" {
				if runtime.focusedItem == nil {
					err = errors.New("focused item unavailable")
				} else {
					item, err = runtime.focusedItem(itemCtx)
				}
			} else {
				item, err = readTentacleClipboard(itemCtx)
				if item.Temporary {
					temporaryFiles = append(temporaryFiles, item.Path)
					item.Temporary = false
				}
			}
			stopItem()
			if err != nil {
				submission.Error = "The requested item is unavailable or is not a single item"
			} else {
				submission.Item = &item
			}
		}
		// A cancelled UI still gets a short cleanup invocation while its session is
		// live. That lets the tentacle stop its background process on Escape/focus loss.
		raw, err = runtime.callInteraction(ctx, command, value.Next, submission)
		if err != nil {
			return
		}
		if submission.Cancelled {
			return
		}
	}
}

func (runtime *tentacleRuntime) validContinuation(command tentacleCommand, id string) bool {
	if id == "" {
		return true
	}
	for _, registered := range command.session.Commands() {
		if registered.ID == id {
			return registered.Interaction && registered.Presentation
		}
	}
	return false
}
func (runtime *tentacleRuntime) callInteraction(ctx context.Context, command tentacleCommand, id string, arguments any) (json.RawMessage, error) {
	data, err := json.Marshal(arguments)
	if err != nil {
		return nil, err
	}
	replies, err := command.session.Invoke(ctx, id, data)
	if err != nil {
		return nil, err
	}
	result := <-replies
	return result.Value, result.Err
}
func (runtime *tentacleRuntime) waitTentacleForm(ctx context.Context, command tentacleCommand, value tentaclewire.Interaction, replies <-chan internalUIResult) (internalUIResult, json.RawMessage) {
	var ticks <-chan time.Time
	if value.Poll != "" {
		ticker := time.NewTicker(time.Second)
		defer ticker.Stop()
		ticks = ticker.C
	}
	for {
		select {
		case reply := <-replies:
			return reply, nil
		case <-ctx.Done():
			return internalUIResult{Cancelled: true}, nil
		case <-ticks:
			raw, err := runtime.callInteraction(ctx, command, value.Poll, tentaclewire.Submission{})
			if err != nil {
				return internalUIResult{Cancelled: true}, nil
			}
			status, err := tentaclewire.DecodeInteraction(raw)
			if err != nil || status.Form != nil || status.Source != "" || status.Next != "" {
				command.session.Disable()
				return internalUIResult{Cancelled: true}, nil
			}
			if status.Done {
				return internalUIResult{}, raw
			}
			if status.Clipboard != nil {
				if runtime.output.gate.Locked() || runtime.output.gate.Suspended() || ctx.Err() != nil {
					return internalUIResult{Cancelled: true}, nil
				}
				copyCtx, stopCopy := context.WithTimeout(ctx, time.Second)
				copyErr := copyTentacleText(copyCtx, *status.Clipboard)
				stopCopy()
				if copyErr != nil {
					status.Presentation = clipboardWriteFailure(status.Presentation)
				}
			}
			runtime.forms.Notice(ctx, status.Presentation)
		}
	}
}

func focusedTentacleItem(source any, ui *internalUI) func(context.Context) (tentaclewire.Item, error) {
	reader, ok := source.(interface {
		ReadTransferItem(context.Context, atspi.ObjectID, int) (atspi.TransferItem, error)
	})
	if !ok || ui.interest == nil {
		return nil
	}
	return func(ctx context.Context) (tentaclewire.Item, error) {
		interest, err := ui.interest.ObjectOfInterest(ctx)
		if err != nil {
			return tentaclewire.Item{}, err
		}
		if interest.HasZone {
			return tentaclewire.Item{}, errors.New("flat review transfer unavailable")
		}
		item, err := reader.ReadTransferItem(ctx, interest.Object, interest.Offset)
		return tentaclewire.Item{Text: item.Text, Path: item.Path}, err
	}
}

func clipboardWriteFailure(message tentaclewire.Presentation) tentaclewire.Presentation {
	if message.Speech == "" {
		message.Speech = "Clipboard text could not be saved"
	} else {
		message.Speech = fmt.Sprintf("%s. Clipboard text could not be saved", message.Speech)
	}
	if message.Braille == "" {
		message.Braille = "Clipboard text could not be saved"
	} else {
		message.Braille = fmt.Sprintf("%s. Clipboard text could not be saved", message.Braille)
	}
	return message
}