// yt - A fully featured command line YouTube client
//
// Copyright (C) 2025 Benedikt Peetz <benedikt.peetz@b-peetz.de>
// SPDX-License-Identifier: GPL-3.0-or-later
//
// This file is part of Yt.
//
// You should have received a copy of the License along with this program.
// If not, see <https://www.gnu.org/licenses/gpl-3.0.txt>.

use curl::easy::Easy;
use log::{error, info, trace, warn};
use pyo3::{
    Bound, PyAny, PyErr, PyResult, Python, exceptions, intern, pyfunction,
    types::{PyAnyMethods, PyDict, PyModule},
    wrap_pyfunction,
};
use serde::{Deserialize, Serialize};

use crate::{
    pydict_cast, pydict_get,
    python_error::{IntoPythonError, PythonError},
};

/// # Errors
/// - If the underlying function returns an error.
/// - If python operations fail.
pub fn process(py: Python<'_>) -> PyResult<Bound<'_, PyAny>> {
    #[pyfunction]
    fn actual_processor(info_json: Bound<'_, PyDict>) -> PyResult<Bound<'_, PyDict>> {
        let output = match unwrapped_process(info_json) {
            Ok(ok) => ok,
            Err(err) => {
                return Err(PyErr::new::<exceptions::PyRuntimeError, _>(err.to_string()));
            }
        };
        Ok(output)
    }

    let module = PyModule::new(py, "rust_post_processors")?;
    let scope = PyDict::new(py);
    scope.set_item(
        intern!(py, "actual_processor"),
        wrap_pyfunction!(actual_processor, module)?,
    )?;
    py.run(
        c"
import yt_dlp

class DeArrow(yt_dlp.postprocessor.PostProcessor):
    def run(self, info):
        info = actual_processor(info)
        return [], info

inst = DeArrow()
",
        Some(&scope),
        None,
    )?;

    Ok(scope.get_item(intern!(py, "inst"))?.downcast_into()?)
}

/// # Errors
/// If the API access fails.
pub fn unwrapped_process(info: Bound<'_, PyDict>) -> Result<Bound<'_, PyDict>, Error> {
    if pydict_get!(info, "extractor_key", String).as_str() != "Youtube" {
        return Ok(info);
    }

    let mut retry_num = 3;
    let mut output: DeArrowApi = {
        loop {
            let output_bytes = {
                let mut dst = Vec::new();

                let mut easy = Easy::new();
                easy.url(
                    format!(
                        "https://sponsor.ajay.app/api/branding?videoID={}",
                        pydict_get!(info, "id", String)
                    )
                    .as_str(),
                )?;

                let mut transfer = easy.transfer();
                transfer.write_function(|data| {
                    dst.extend_from_slice(data);
                    Ok(data.len())
                })?;
                transfer.perform()?;
                drop(transfer);

                dst
            };

            match serde_json::from_slice(&output_bytes) {
                Ok(ok) => break ok,
                Err(err) => {
                    if retry_num > 0 {
                        trace!(
                            "DeArrow: Api access failed, trying again ({retry_num} retries left)"
                        );
                        retry_num -= 1;
                    } else {
                        let err: serde_json::Error = err;
                        return Err(err.into());
                    }
                }
            }
        }
    };

    // We pop the titles, so we need this vector reversed.
    output.titles.reverse();

    let title_len = output.titles.len();
    let mut iterator = output.titles.clone();
    let selected = loop {
        let Some(title) = iterator.pop() else {
            break false;
        };

        if (title.locked || title.votes < 1) && title_len > 1 {
            info!(
                "DeArrow: Skipping title {:#?}, as it is not good enough",
                title.value
            );
            // Skip titles that are not “good” enough.
            continue;
        }

        update_title(&info, &title.value).wrap_exc(info.py())?;

        break true;
    };

    if !selected && title_len != 0 {
        // No title was selected, even though we had some titles.
        // Just pick the first one in this case.
        update_title(&info, &output.titles[0].value).wrap_exc(info.py())?;
    }

    Ok(info)
}

#[derive(thiserror::Error, Debug)]
pub enum Error {
    #[error(transparent)]
    Python(#[from] PythonError),

    #[error("Failed to access the DeArrow api: {0}")]
    Get(#[from] curl::Error),

    #[error("Failed to deserialize a api json return object: {0}")]
    Deserialize(#[from] serde_json::Error),
}

fn update_title(info: &Bound<'_, PyDict>, new_title: &str) -> PyResult<()> {
    let py = info.py();

    assert!(!info.contains(intern!(py, "original_title"))?);

    if let Ok(old_title) = info.get_item(intern!(py, "title")) {
        warn!(
            "DeArrow: Updating title from {:#?} to {:#?}",
            pydict_cast!(old_title, &str),
            new_title
        );

        info.set_item(intern!(py, "original_title"), old_title)
            .expect("We checked, it is a new key");
    } else {
        warn!("DeArrow: Setting title to {new_title:#?}");
    }

    let cleaned_title = {
        // NOTE(@bpeetz): DeArrow uses `>` as a “Don't format the next word” mark.
        // They should be removed, if one does not use a auto-formatter. <2025-06-16>
        new_title.replace('>', "")
    };

    info.set_item(intern!(py, "title"), cleaned_title)
        .expect("This should work?");

    Ok(())
}

#[derive(Serialize, Deserialize)]
/// See: <https://wiki.sponsor.ajay.app/w/API_Docs/DeArrow>
struct DeArrowApi {
    titles: Vec<Title>,
    thumbnails: Vec<Thumbnail>,

    #[serde(alias = "randomTime")]
    random_time: Option<f64>,

    #[serde(alias = "videoDuration")]
    video_duration: Option<f64>,

    #[serde(alias = "casualVotes")]
    casual_votes: Vec<CasualVote>,
}

#[derive(Serialize, Deserialize)]
struct CasualVote {
    id: String,
    count: u32,
    title: String,
}

#[derive(Serialize, Deserialize, Clone)]
struct Title {
    /// Note: Titles will sometimes contain > before a word.
    /// This tells the auto-formatter to not format a word.
    /// If you have no auto-formatter, you can ignore this and replace it with an empty string
    #[serde(alias = "title")]
    value: String,

    original: bool,
    votes: u64,
    locked: bool,

    #[serde(alias = "UUID")]
    uuid: String,

    /// only present if requested
    #[serde(alias = "userID")]
    user_id: Option<String>,
}

#[derive(Serialize, Deserialize)]
struct Thumbnail {
    // null if original is true
    timestamp: Option<f64>,

    original: bool,
    votes: u64,
    locked: bool,

    #[serde(alias = "UUID")]
    uuid: String,

    /// only present if requested
    #[serde(alias = "userID")]
    user_id: Option<String>,
}