use super::{
    message::*, patch_system_message, Client, ExtraConfig, Model, PromptType, SendData,
    TokensCountFactors, VertexAIClient,
};

use crate::{render::ReplyHandler, utils::PromptKind};

use anyhow::{anyhow, bail, Context, Result};
use async_trait::async_trait;
use chrono::{Duration, Utc};
use futures_util::StreamExt;
use reqwest::{Client as ReqwestClient, RequestBuilder};
use serde::Deserialize;
use serde_json::{json, Value};
use std::path::PathBuf;

const MODELS: [(&str, usize, &str); 3] = [
    // https://cloud.google.com/vertex-ai/generative-ai/docs/learn/models
    ("gemini-1.0-pro", 24568, "text"),
    ("gemini-1.0-pro-vision", 14336, "text,vision"),
    ("gemini-1.5-pro-preview-0409", 1000000, "text,vision"),
];

const TOKENS_COUNT_FACTORS: TokensCountFactors = (5, 2);

static mut ACCESS_TOKEN: (String, i64) = (String::new(), 0); // safe under linear operation

#[derive(Debug, Clone, Deserialize, Default)]
pub struct VertexAIConfig {
    pub name: Option<String>,
    pub api_base: Option<String>,
    pub adc_file: Option<String>,
    pub block_threshold: Option<String>,
    pub extra: Option<ExtraConfig>,
}

#[async_trait]
impl Client for VertexAIClient {
    client_common_fns!();

    async fn send_message_inner(&self, client: &ReqwestClient, data: SendData) -> Result<String> {
        self.prepare_access_token().await?;
        let builder = self.request_builder(client, data)?;
        send_message(builder).await
    }

    async fn send_message_streaming_inner(
        &self,
        client: &ReqwestClient,
        handler: &mut ReplyHandler,
        data: SendData,
    ) -> Result<()> {
        self.prepare_access_token().await?;
        let builder = self.request_builder(client, data)?;
        send_message_streaming(builder, handler).await
    }
}

impl VertexAIClient {
    config_get_fn!(api_base, get_api_base);

    pub const PROMPTS: [PromptType<'static>; 1] =
        [("api_base", "API Base:", true, PromptKind::String)];

    pub fn list_models(local_config: &VertexAIConfig) -> Vec<Model> {
        let client_name = Self::name(local_config);
        MODELS
            .into_iter()
            .map(|(name, max_input_tokens, capabilities)| {
                Model::new(client_name, name)
                    .set_capabilities(capabilities.into())
                    .set_max_input_tokens(Some(max_input_tokens))
                    .set_tokens_count_factors(TOKENS_COUNT_FACTORS)
            })
            .collect()
    }

    fn request_builder(&self, client: &ReqwestClient, data: SendData) -> Result<RequestBuilder> {
        let api_base = self.get_api_base()?;

        let func = match data.stream {
            true => "streamGenerateContent",
            false => "generateContent",
        };

        let block_threshold = self.config.block_threshold.clone();

        let body = build_body(data, self.model.name.clone(), block_threshold)?;

        let model = self.model.name.clone();

        let url = format!("{api_base}/{}:{}", model, func);

        debug!("VertexAI Request: {url} {body}");

        let builder = client
            .post(url)
            .bearer_auth(unsafe { &ACCESS_TOKEN.0 })
            .json(&body);

        Ok(builder)
    }

    async fn prepare_access_token(&self) -> Result<()> {
        if unsafe { ACCESS_TOKEN.0.is_empty() || Utc::now().timestamp() > ACCESS_TOKEN.1 } {
            let client = self.build_client()?;
            let (token, expires_in) = fetch_access_token(&client, &self.config.adc_file)
                .await
                .with_context(|| "Failed to fetch access token")?;
            let expires_at = Utc::now()
                + Duration::try_seconds(expires_in)
                    .ok_or_else(|| anyhow!("Failed to parse expires_in of access_token"))?;
            unsafe { ACCESS_TOKEN = (token, expires_at.timestamp()) };
        }
        Ok(())
    }
}

pub(crate) async fn send_message(builder: RequestBuilder) -> Result<String> {
    let res = builder.send().await?;
    let status = res.status();
    let data: Value = res.json().await?;
    if status != 200 {
        check_error(&data)?;
    }
    let output = extract_text(&data)?;
    Ok(output.to_string())
}

pub(crate) async fn send_message_streaming(
    builder: RequestBuilder,
    handler: &mut ReplyHandler,
) -> Result<()> {
    let res = builder.send().await?;
    if res.status() != 200 {
        let data: Value = res.json().await?;
        check_error(&data)?;
    } else {
        let mut buffer = vec![];
        let mut cursor = 0;
        let mut start = 0;
        let mut balances = vec![];
        let mut quoting = false;
        let mut stream = res.bytes_stream();
        while let Some(chunk) = stream.next().await {
            let chunk = chunk?;
            let chunk = std::str::from_utf8(&chunk)?;
            buffer.extend(chunk.chars());
            for i in cursor..buffer.len() {
                let ch = buffer[i];
                if quoting {
                    if ch == '"' && buffer[i - 1] != '\\' {
                        quoting = false;
                    }
                    continue;
                }
                match ch {
                    '"' => quoting = true,
                    '{' => {
                        if balances.is_empty() {
                            start = i;
                        }
                        balances.push(ch);
                    }
                    '[' => {
                        if start != 0 {
                            balances.push(ch);
                        }
                    }
                    '}' => {
                        balances.pop();
                        if balances.is_empty() {
                            let value: String = buffer[start..=i].iter().collect();
                            let value: Value = serde_json::from_str(&value)?;
                            handler.text(extract_text(&value)?)?;
                        }
                    }
                    ']' => {
                        balances.pop();
                    }
                    _ => {}
                }
            }
            cursor = buffer.len();
        }
    }
    Ok(())
}

fn extract_text(data: &Value) -> Result<&str> {
    match data["candidates"][0]["content"]["parts"][0]["text"].as_str() {
        Some(text) => Ok(text),
        None => {
            if let Some("SAFETY") = data["promptFeedback"]["blockReason"]
                .as_str()
                .or_else(|| data["candidates"][0]["finishReason"].as_str())
            {
                bail!("Blocked by safety settings，consider adjusting `block_threshold` in the client configuration")
            } else {
                bail!("Invalid response data: {data}")
            }
        }
    }
}

fn check_error(data: &Value) -> Result<()> {
    if let Some((Some(status), Some(message))) = data[0]["error"].as_object().map(|v| {
        (
            v.get("status").and_then(|v| v.as_str()),
            v.get("message").and_then(|v| v.as_str()),
        )
    }) {
        if status == "UNAUTHENTICATED" {
            unsafe { ACCESS_TOKEN = (String::new(), 0) }
        }
        bail!("{status}: {message}")
    } else {
        bail!("Error {}", data);
    }
}

pub(crate) fn build_body(
    data: SendData,
    _model: String,
    block_threshold: Option<String>,
) -> Result<Value> {
    let SendData {
        mut messages,
        temperature,
        ..
    } = data;

    patch_system_message(&mut messages);

    let mut network_image_urls = vec![];
    let contents: Vec<Value> = messages
        .into_iter()
        .map(|message| {
            let role = match message.role {
                MessageRole::User => "user",
                _ => "model",
            };
            match message.content {
                MessageContent::Text(text) => json!({
                    "role": role,
                    "parts": [{ "text": text }]
                }),
                MessageContent::Array(list) => {
                    let list: Vec<Value> = list
                        .into_iter()
                        .map(|item| match item {
                            MessageContentPart::Text { text } => json!({"text": text}),
                            MessageContentPart::ImageUrl { image_url: ImageUrl { url } } => {
                                if let Some((mime_type, data)) = url.strip_prefix("data:").and_then(|v| v.split_once(";base64,")) {
                                    json!({ "inline_data": { "mime_type": mime_type, "data": data } })
                                } else {
                                    network_image_urls.push(url.clone());
                                    json!({ "url": url })
                                }
                            },
                        })
                        .collect();
                    json!({ "role": role, "parts": list })
                }
            }
        })
        .collect();

    if !network_image_urls.is_empty() {
        bail!(
            "The model does not support network images: {:?}",
            network_image_urls
        );
    }

    let mut body = json!({ "contents": contents });

    if let Some(block_threshold) = block_threshold {
        body["safetySettings"] = json!([
            {"category":"HARM_CATEGORY_HARASSMENT","threshold":block_threshold},
            {"category":"HARM_CATEGORY_HATE_SPEECH","threshold":block_threshold},
            {"category":"HARM_CATEGORY_SEXUALLY_EXPLICIT","threshold":block_threshold},
            {"category":"HARM_CATEGORY_DANGEROUS_CONTENT","threshold":block_threshold}
        ]);
    }

    if let Some(temperature) = temperature {
        body["generationConfig"] = json!({
            "temperature": temperature,
        });
    }

    Ok(body)
}

async fn fetch_access_token(
    client: &reqwest::Client,
    file: &Option<String>,
) -> Result<(String, i64)> {
    let credentials = load_adc(file).await?;
    let value: Value = client
        .post("https://oauth2.googleapis.com/token")
        .json(&credentials)
        .send()
        .await?
        .json()
        .await?;

    if let (Some(access_token), Some(expires_in)) =
        (value["access_token"].as_str(), value["expires_in"].as_i64())
    {
        Ok((access_token.to_string(), expires_in))
    } else if let Some(err_msg) = value["error_description"].as_str() {
        bail!("{err_msg}")
    } else {
        bail!("Invalid response data")
    }
}

async fn load_adc(file: &Option<String>) -> Result<Value> {
    let adc_file = file
        .as_ref()
        .map(PathBuf::from)
        .or_else(default_adc_file)
        .ok_or_else(|| anyhow!("No application_default_credentials.json"))?;
    let data = tokio::fs::read_to_string(adc_file).await?;
    let data: Value = serde_json::from_str(&data)?;
    if let (Some(client_id), Some(client_secret), Some(refresh_token)) = (
        data["client_id"].as_str(),
        data["client_secret"].as_str(),
        data["refresh_token"].as_str(),
    ) {
        Ok(json!({
            "client_id": client_id,
            "client_secret": client_secret,
            "refresh_token": refresh_token,
            "grant_type": "refresh_token",
        }))
    } else {
        bail!("Invalid application_default_credentials.json")
    }
}

#[cfg(not(windows))]
fn default_adc_file() -> Option<PathBuf> {
    let mut path = dirs::home_dir()?;
    path.push(".config");
    path.push("gcloud");
    path.push("application_default_credentials.json");
    Some(path)
}

#[cfg(windows)]
fn default_adc_file() -> Option<PathBuf> {
    let mut path = dirs::config_dir()?;
    path.push("gcloud");
    path.push("application_default_credentials.json");
    Some(path)
}