// Copyright (c) 2026 Storm Dragon
// Authors: Storm Dragon, Angus Kola
// SPDX-License-Identifier: GPL-3.0-or-later

package speech

import (
	"context"
	"errors"
	"fmt"
	"strings"
	"unicode/utf8"
)

// Fragment is literal text with resolved spelling/language state. A fragment
// boundary is a synthesis boundary; callers coalesce transport fragments first.
// Empty language selects this client's effective configured default language.
type Fragment struct {
	Text       string
	Characters bool
	Language   string
}

// SpeakFragmentsAndWait is for an isolated output owner. Unlike ordinary local
// speech, it preserves spaces/tabs and line boundaries (canonicalized to CRLF).
// Plain-text mode prevents network text being interpreted as synthesis markup.
// It validates the entire sequence before any backend operation, then retains
// the speaking lock through every END/CANCEL. Cancel still uses its own channel.
// This method implements no priority, lease, pause or local-focus policy.
func (client *Client) SpeakFragmentsAndWait(ctx context.Context, fragments []Fragment) (result error) {
	if len(fragments) == 0 || len(fragments) > 8192 {
		return errors.New("invalid speech fragment count")
	}
	bytes := 0
	for _, part := range fragments {
		bytes += len(part.Text)
		if bytes > 256*1024 || !valid_fragment(part) {
			return errors.New("invalid speech fragment")
		}
	}
	client.mutex.Lock()
	defer client.mutex.Unlock()
	if client.conn == nil {
		return errors.New("speech client is not connected")
	}
	defer func() {
		if result != nil {
			result = errors.Join(ctx.Err(), result)
		}
		if result != nil && client.conn != nil {
			_ = client.conn.Close()
			client.conn, client.reader = nil, nil
		}
	}()
	// Query the effective default after initialization: a selected synthesis
	// voice may override SET LANGUAGE, and the server default may be unsaved.
	defaultLanguage, err := client.fragment_parameter(ctx, "LANGUAGE")
	if err != nil || !valid_fragment_language(defaultLanguage, false) {
		return errors.Join(ctx.Err(), errors.New("speech default language unavailable"))
	}
	module, err := client.fragment_parameter(ctx, "OUTPUT_MODULE")
	if err != nil || !valid_fragment_language(module, false) {
		return errors.Join(ctx.Err(), errors.New("speech default module unavailable"))
	}
	voiceType, err := client.fragment_parameter(ctx, "VOICE_TYPE")
	if err != nil {
		return errors.Join(ctx.Err(), errors.New("speech default voice unavailable"))
	}
	switch voiceType {
	case "MALE1", "MALE2", "MALE3", "FEMALE1", "FEMALE2", "FEMALE3", "CHILD_MALE", "CHILD_FEMALE":
	case "NO_VOICE":
		if client.settings.SynthesisVoice == "" {
			return errors.New("speech default voice unavailable")
		}
		// A named voice has no portable gender/category. Explicit remote
		// languages use the SSIP baseline category instead of that voice name.
		voiceType = "MALE1"
	default:
		return errors.New("speech default voice unavailable")
	}
	setVoice := func(language, named string) error {
		// SET LANGUAGE can select a different output module via server config.
		// Restore the reader's actual module, then clear any previous named
		// voice through VOICE_TYPE. A default-language part regains its name.
		for _, fields := range [][]string{
			{"SET", "SELF", "LANGUAGE", language},
			{"SET", "SELF", "OUTPUT_MODULE", module},
			{"SET", "SELF", "VOICE_TYPE", voiceType},
		} {
			if err := client.sendCommand(ctx, fields); err != nil {
				return err
			}
		}
		if named != "" {
			return client.sendCommand(ctx, []string{"SET", "SELF", "SYNTHESIS_VOICE", named})
		}
		return nil
	}
	if err := client.sendCommand(ctx, []string{"SET", "SELF", "SSML_MODE", "off"}); err != nil {
		return err
	}
	for _, part := range fragments {
		language, spelling, named := part.Language, "off", ""
		if language == "" {
			language, named = defaultLanguage, client.settings.SynthesisVoice
		}
		if err := setVoice(language, named); err != nil {
			return err
		}
		if part.Characters {
			spelling = "on"
		}
		if err := client.sendCommand(ctx, []string{"SET", "SELF", "SPELLING", spelling}); err != nil {
			return err
		}
		text := strings.ReplaceAll(part.Text, "\r\n", "\n")
		text = strings.ReplaceAll(text, "\r", "\n")
		text = strings.ReplaceAll(text, "\n", "\r\n")
		if err := client.speak_and_wait_locked(ctx, func() error { return client.speak_block(ctx, text) }, nil); err != nil {
			return err
		}
	}
	if err := client.sendCommand(ctx, []string{"SET", "SELF", "SPELLING", "off"}); err != nil {
		return err
	}
	return setVoice(defaultLanguage, client.settings.SynthesisVoice)
}

// These names are fixed by the caller; response values never become commands
// until their bounded token/enum validators have accepted them.
func (client *Client) fragment_parameter(ctx context.Context, name string) (string, error) {
	finish, err := prepareIO(ctx, client.conn, client.ioTimeout)
	if err != nil {
		return "", err
	}
	defer finish()
	_, err = fmt.Fprint(client.conn, "GET "+name+"\r\n")
	var response reply
	if err == nil {
		response, err = client.readReply()
	}
	if err != nil || response.code != 251 || len(response.data) != 1 {
		return "", errors.New("speech default unavailable")
	}
	return response.data[0], nil
}

func valid_fragment(part Fragment) bool {
	if part.Text == "" || !utf8.ValidString(part.Text) || !valid_fragment_language(part.Language, true) {
		return false
	}
	for _, character := range part.Text {
		if character < 32 && character != '\r' && character != '\n' && character != '\t' || character == 127 {
			return false
		}
	}
	return true
}

func valid_fragment_language(language string, empty bool) bool {
	if language == "" {
		return empty
	}
	if len(language) > 64 {
		return false
	}
	for _, character := range language {
		if !(character >= 'a' && character <= 'z' || character >= 'A' && character <= 'Z' || character >= '0' && character <= '9' || character == '-' || character == '_') {
			return false
		}
	}
	return true
}