use crate::errors::SyncError;
use dissimilar::Chunk;
use document_model::document::DocumentInfo;
use lib_ot::core::{DeltaOperationBuilder, OTString, OperationAttributes};
use lib_ot::{
    core::{DeltaOperations, OperationTransform, NEW_LINE, WHITESPACE},
    text_delta::DeltaTextOperations,
};
use revision_model::Revision;
use serde::de::DeserializeOwned;

#[inline]
pub fn find_newline(s: &str) -> Option<usize> {
    s.find(NEW_LINE)
}

#[inline]
pub fn is_newline(s: &str) -> bool {
    s == NEW_LINE
}

#[inline]
pub fn is_whitespace(s: &str) -> bool {
    s == WHITESPACE
}

#[inline]
pub fn contain_newline(s: &str) -> bool {
    s.contains(NEW_LINE)
}

pub fn recover_operation_from_revisions<T>(
    revisions: Vec<Revision>,
    validator: impl Fn(&DeltaOperations<T>) -> bool,
) -> Option<DeltaOperations<T>>
where
    T: OperationAttributes + DeserializeOwned + OperationAttributes,
{
    let mut new_operations = DeltaOperations::<T>::new();
    for revision in revisions {
        if let Ok(operations) = DeltaOperations::<T>::from_bytes(revision.bytes) {
            match new_operations.compose(&operations) {
                Ok(composed_operations) => {
                    if validator(&composed_operations) {
                        new_operations = composed_operations;
                    } else {
                        break;
                    }
                }
                Err(_) => break,
            }
        } else {
            break;
        }
    }
    if new_operations.is_empty() {
        None
    } else {
        Some(new_operations)
    }
}

#[inline]
pub fn make_document_info_from_revisions(
    doc_id: &str,
    revisions: Vec<Revision>,
) -> Result<Option<DocumentInfo>, SyncError> {
    if revisions.is_empty() {
        return Ok(None);
    }

    let mut delta = DeltaTextOperations::new();
    let mut base_rev_id = 0;
    let mut rev_id = 0;
    for revision in revisions {
        base_rev_id = revision.base_rev_id;
        rev_id = revision.rev_id;

        if revision.bytes.is_empty() {
            tracing::warn!("revision delta_data is empty");
        }

        let new_delta = DeltaTextOperations::from_bytes(revision.bytes)?;
        delta = delta.compose(&new_delta)?;
    }

    Ok(Some(DocumentInfo {
        doc_id: doc_id.to_owned(),
        data: delta.json_bytes().to_vec(),
        rev_id,
        base_rev_id,
    }))
}

#[inline]
pub fn rev_id_from_str(s: &str) -> Result<i64, SyncError> {
    let rev_id = s
        .to_owned()
        .parse::<i64>()
        .map_err(|e| SyncError::internal().context(format!("Parse rev_id from {} failed. {}", s, e)))?;
    Ok(rev_id)
}

pub fn cal_diff<T: OperationAttributes>(old: String, new: String) -> Option<DeltaOperations<T>> {
    let chunks = dissimilar::diff(&old, &new);
    let mut delta_builder = DeltaOperationBuilder::<T>::new();
    for chunk in &chunks {
        match chunk {
            Chunk::Equal(s) => {
                delta_builder = delta_builder.retain(OTString::from(*s).utf16_len());
            }
            Chunk::Delete(s) => {
                delta_builder = delta_builder.delete(OTString::from(*s).utf16_len());
            }
            Chunk::Insert(s) => {
                delta_builder = delta_builder.insert(s);
            }
        }
    }

    let delta = delta_builder.build();
    if delta.is_empty() {
        None
    } else {
        Some(delta)
    }
}