use std::io::Read;
use std::path::{Path, PathBuf};

use reqwest::blocking::multipart::{Form, Part};
use serde::{Deserialize, Serialize};

use crate::diagnostics::{record_audio_size, tail, TranscriptionAttempt};
use crate::error::{AppError, AppResult};
use crate::secrets::SecretReader;

use super::{Transcriber, TranscriptionInput, TranscriptionResult};

/// Configuração para transcrição via API compatível com OpenAI.
///
/// Esta config **não** armazena a `api_key` em texto claro. A chave é obtida
/// via `SecretReader` (credential manager do SO) no momento da requisição,
/// e a presença dela é reportada pelo flag `api_key_configured`.
#[derive(Debug, Clone, Serialize, Deserialize, PartialEq, Eq)]
#[serde(rename_all = "camelCase")]
pub struct OpenAiTranscriptionConfig {
    /// URL completa do endpoint (ex.: `http://localhost:8022/v1/audio/transcriptions`).
    pub endpoint: String,
    /// Modelo a ser enviado (ex.: `whisper-1`, `Systrim/Kokoro-TTS`).
    pub model: String,
    /// Idioma opcional no formato ISO-639-1 (ex.: `"pt"`, `"en"`).
    pub language: Option<String>,
    /// Apenas indica se existe uma api_key salva; nunca exposto para a UI.
    pub api_key_configured: bool,
}

impl Default for OpenAiTranscriptionConfig {
    fn default() -> Self {
        Self {
            endpoint: "http://localhost:8022/v1/audio/transcriptions".to_string(),  // Parakeet local default
            model: "alefiury/parakeet-tdt-0.6b-v3-ptBR-TAGARELA-onnx".to_string(),  // PT-BR nativo
            language: None,
            api_key_configured: false,
        }
    }
}

impl OpenAiTranscriptionConfig {
    /// Mesma config mas com o flag `api_key_configured` refletindo o estado real.
    pub fn with_key_state(mut self, configured: bool) -> Self {
        self.api_key_configured = configured;
        self
    }
}

/// Transcritor que envia o WAV para o endpoint compatível com OpenAI.
#[derive(Clone)]
pub struct OpenAiTranscriber {
    config: OpenAiTranscriptionConfig,
    /// Fonte de leitura da `api_key` (credential manager do SO).
    secrets: std::sync::Arc<dyn SecretReader>,
}

impl std::fmt::Debug for OpenAiTranscriber {
    fn fmt(&self, formatter: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        formatter
            .debug_struct("OpenAiTranscriber")
            .field("config", &self.config)
            .finish_non_exhaustive()
    }
}

impl OpenAiTranscriber {
    pub fn new(
        config: OpenAiTranscriptionConfig,
        secrets: std::sync::Arc<dyn SecretReader>,
    ) -> Self {
        Self { config, secrets }
    }

    pub fn config(&self) -> &OpenAiTranscriptionConfig {
        &self.config
    }

    pub fn endpoint(&self) -> &str {
        &self.config.endpoint
    }

    pub fn model(&self) -> &str {
        &self.config.model
    }

    pub fn language(&self) -> Option<&str> {
        self.config.language.as_deref()
    }
}

impl Transcriber for OpenAiTranscriber {
    fn transcribe(&self, input: TranscriptionInput) -> AppResult<TranscriptionResult> {
        let audio_path: &Path = &input.audio_path;
        let audio_size = record_audio_size(audio_path);
        if audio_size == 0 {
            return Err(AppError::Audio(format!(
                "WAV gravado está vazio: {}",
                audio_path.display()
            )));
        }

        if self.config.endpoint.trim().is_empty() {
            return Err(AppError::Configuration(
                "Endpoint da API compatível com OpenAI não configurado.".to_string(),
            ));
        }
        if self.config.model.trim().is_empty() {
            return Err(AppError::Configuration(
                "Modelo da API compatível com OpenAI não configurado.".to_string(),
            ));
        }

        let attempt = TranscriptionAttempt {
            stage: "openai_request".to_string(),
            audio_path: PathBuf::from(audio_path),
            audio_size_bytes: audio_size,
            sidecar: "openai-compat-http".to_string(),
            model: self.config.model.clone(),
            exit_code: None,
            stdout_tail: String::new(),
            stderr_tail: String::new(),
            error: None,
        };

        let api_key = self.secrets.read_api_key().ok().flatten();

        let response = match send_transcription_request(
            &self.config.endpoint,
            &self.config.model,
            self.config.language.as_deref(),
            audio_path,
            api_key.as_deref(),
        ) {
            Ok(text) => text,
            Err(error) => {
                return Err(AppError::Transcription(format!(
                    "{error} (modelo={}, endpoint={})",
                    self.config.model, self.config.endpoint
                )));
            }
        };

        let text = response.trim().to_string();
        if text.is_empty() {
            return Err(AppError::Transcription(
                "API retornou resposta vazia.".to_string(),
            ));
        }

        let mut ok_attempt = attempt;
        ok_attempt.stage = "ok".to_string();
        ok_attempt.stdout_tail = tail(&text, 1024);

        Ok(TranscriptionResult {
            text,
            backend: "openai-compat".to_string(),
            model_id: self.config.model.clone(),
            detected_language: self.config.language.clone(),
            attempt: Some(ok_attempt),
        })
    }
}

fn send_transcription_request(
    endpoint: &str,
    model: &str,
    language: Option<&str>,
    audio_path: &Path,
    api_key: Option<&str>,
) -> Result<String, String> {
    let mut file = std::fs::File::open(audio_path)
        .map_err(|error| format!("falha ao abrir áudio: {error}"))?;
    let mut bytes = Vec::new();
    file.read_to_end(&mut bytes)
        .map_err(|error| format!("falha ao ler áudio: {error}"))?;

    let file_name = audio_path
        .file_name()
        .and_then(|name| name.to_str())
        .unwrap_or("audio.wav")
        .to_string();

    let audio_part = Part::bytes(bytes)
        .file_name(file_name)
        .mime_str("audio/wav")
        .map_err(|error| format!("mime inválido: {error}"))?;

    let mut form = Form::new()
        .text("model", model.to_string())
        .part("file", audio_part);

    if let Some(lang) = language {
        if !lang.trim().is_empty() {
            form = form.text("language", lang.to_string());
        }
    }

    let client = reqwest::blocking::Client::builder()
        .timeout(std::time::Duration::from_secs(120))
        .build()
        .map_err(|error| format!("cliente HTTP inválido: {error}"))?;

    let mut request = client.post(endpoint).multipart(form);
    if let Some(key) = api_key {
        if !key.trim().is_empty() {
            request = request.bearer_auth(key);
        }
    }

    let response = request
        .send()
        .map_err(|error| format!("falha na requisição: {error}"))?;

    let status = response.status();
    let body = response
        .text()
        .map_err(|error| format!("falha ao ler corpo: {error}"))?;

    if !status.is_success() {
        return Err(format!(
            "API respondeu {status}: {}",
            body.chars().take(400).collect::<String>()
        ));
    }

    // Formato OpenAI padrão: `{"text": "..."}`.
    if let Ok(parsed) = serde_json::from_str::<OpenAiTranscriptionResponse>(&body) {
        if let Some(text) = parsed.text {
            return Ok(text);
        }
    }

    let trimmed = body.trim();
    // Texto puro: o servidor devolve a transcrição sem envelopar em JSON.
    if !trimmed.is_empty() && !trimmed.starts_with('{') && !trimmed.starts_with('[') {
        return Ok(trimmed.to_string());
    }

    // Alguns provedores customizam o nome do campo. Tentamos várias chaves.
    if let Ok(value) = serde_json::from_str::<serde_json::Value>(&body) {
        for key in ["text", "transcript", "result", "output", "data"] {
            if let Some(text) = value.get(key).and_then(|v| v.as_str()) {
                return Ok(text.to_string());
            }
        }
    }

    Err(format!(
        "não foi possível extrair texto da resposta da API: {}",
        body.chars().take(400).collect::<String>()
    ))
}

#[derive(Debug, Deserialize)]
struct OpenAiTranscriptionResponse {
    text: Option<String>,
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn default_endpoint_targets_local_speaches() {
        let config = OpenAiTranscriptionConfig::default();
        assert_eq!(
            config.endpoint,
            "http://localhost:8022/v1/audio/transcriptions"
        );
        assert_eq!(config.model, "alefiury/parakeet-tdt-0.6b-v3-ptBR-TAGARELA-onnx");
        assert!(!config.api_key_configured);
    }

    #[test]
    fn with_key_state_reflects_credential() {
        let config = OpenAiTranscriptionConfig::default().with_key_state(true);
        assert!(config.api_key_configured);

        let config = OpenAiTranscriptionConfig::default().with_key_state(false);
        assert!(!config.api_key_configured);
    }
}