use rayon::iter::{ParallelBridge, ParallelIterator};

use super::DocumentChanges;
use crate::documents::{DocumentIdExtractionError, PrimaryKey};
use crate::update::concurrent_available_ids::ConcurrentAvailableIds;
use crate::update::new::{DocumentChange, Insertion, KvWriterFieldId};
use crate::{all_obkv_to_json, Error, FieldsIdsMap, Object, Result, UserError};

pub struct PartialDump<I> {
    pub iter: I,
}

impl<I> PartialDump<I> {
    pub fn new_from_jsonlines(iter: I) -> Self {
        PartialDump { iter }
    }
}

impl<'p, I> DocumentChanges<'p> for PartialDump<I>
where
    I: IntoIterator<Item = Object>,
    I::IntoIter: Send + 'p,
    I::Item: Send,
{
    type Parameter = (&'p FieldsIdsMap, &'p ConcurrentAvailableIds, &'p PrimaryKey<'p>);

    /// Note for future self:
    ///   - the field ids map must already be valid so you must have to generate it beforehand.
    ///   - We should probably expose another method that generates the fields ids map from an iterator of JSON objects.
    ///   - We recommend sending chunks of documents in this `PartialDumpIndexer` we therefore need to create a custom take_while_size method (that doesn't drop items).
    fn document_changes(
        self,
        param: Self::Parameter,
    ) -> Result<impl ParallelIterator<Item = Result<DocumentChange>> + 'p> {
        let (fields_ids_map, concurrent_available_ids, primary_key) = param;

        Ok(self.iter.into_iter().par_bridge().map(|object| {
            let docid = match concurrent_available_ids.next() {
                Some(id) => id,
                None => return Err(Error::UserError(UserError::DocumentLimitReached)),
            };

            let mut writer = KvWriterFieldId::memory();
            object.iter().for_each(|(key, value)| {
                let key = fields_ids_map.id(key).unwrap();
                /// TODO better error management
                let value = serde_json::to_vec(&value).unwrap();
                /// TODO it is not ordered
                writer.insert(key, value).unwrap();
            });

            let document = writer.into_boxed();
            let external_docid = match primary_key.document_id(&document, fields_ids_map)? {
                Ok(document_id) => Ok(document_id),
                Err(DocumentIdExtractionError::InvalidDocumentId(user_error)) => Err(user_error),
                Err(DocumentIdExtractionError::MissingDocumentId) => {
                    Err(UserError::MissingDocumentId {
                        primary_key: primary_key.name().to_string(),
                        document: all_obkv_to_json(&document, fields_ids_map)?,
                    })
                }
                Err(DocumentIdExtractionError::TooManyDocumentIds(_)) => {
                    Err(UserError::TooManyDocumentIds {
                        primary_key: primary_key.name().to_string(),
                        document: all_obkv_to_json(&document, fields_ids_map)?,
                    })
                }
            }?;

            let insertion = Insertion::create(docid, external_docid, document);
            Ok(DocumentChange::Insertion(insertion))
        }))
    }
}