use crate::addressing::Address;
use crate::database::{
    DbExecutor, Entry, EntryValue, InnerEntry, InsertEntry, QueryEntries, RetrieveByHash,
    RetrieveObject,
};
use crate::hash::{ComputeHash, HasherWorker};
use crate::models;
use anyhow::{anyhow, Result};
use log::{info, trace, warn};
use serde::export::Formatter;
use serde_json::Value;
use std::path::{Component, Path, PathBuf};
use std::{fs, iter};
use walkdir::WalkDir;

use actix::prelude::*;
use chrono::prelude::*;
use uuid::Uuid;

const DIR_KEY: &str = "DIR";
const DIR_HAS_KEY: &str = "DIR_HAS";

const FILE_IDENTITY_KEY: &str = "FILE_IS";
const FILENAME_KEY: &str = "FILE_NAME";

#[derive(Debug, Clone, PartialEq)]
pub struct UDirectory {
    name: String,
}

#[derive(Debug, Clone, PartialEq)]
pub struct UPath(Vec<UDirectory>);

const TOP_SEPARATOR: &str = "//";

impl std::str::FromStr for UPath {
    type Err = anyhow::Error;

    fn from_str(string: &str) -> Result<Self, Self::Err> {
        if string.len() == 0 {
            Ok(UPath(vec![]))
        } else {
            let result = match string.find(TOP_SEPARATOR) {
                Some(head_idx) => {
                    let (head, rest) = string.split_at(head_idx);
                    let mut result: Vec<UDirectory> = Vec::new();
                    result.push(UDirectory {
                        name: String::from(head),
                    });
                    result.append(
                        rest[TOP_SEPARATOR.len()..rest.len()]
                            .trim_end_matches('/')
                            .split("/")
                            .map(|part| UDirectory {
                                name: String::from(part),
                            })
                            .collect::<Vec<UDirectory>>()
                            .as_mut(),
                    );

                    result
                }
                None => string
                    .trim_end_matches('/')
                    .split("/")
                    .map(|part| UDirectory {
                        name: String::from(part),
                    })
                    .collect(),
            };

            for directory in &result {
                if directory.name.len() == 0 {
                    return Err(anyhow!("INVALID PATH: Directory name cannot be empty!"));
                }
            }

            Ok(UPath(result))
        }
    }
}

impl std::fmt::Display for UDirectory {
    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
        write!(f, "{}", self.name)
    }
}

impl std::fmt::Display for UPath {
    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
        match self.0.len() {
            0 => write!(f, ""),
            1 => write!(f, "{}", self.0.first().unwrap().name),
            _ => {
                let (head, tail) = self.0.split_first().unwrap();
                write!(
                    f,
                    "{}//{}",
                    head.name,
                    tail.iter()
                        .map(|udir| udir.name.clone())
                        .collect::<Vec<String>>()
                        .join("/")
                )
            }
        }
    }
}

trait EntryList {
    fn extract_addresses(&self) -> Vec<Address>;
}

impl EntryList for Vec<Entry> {
    fn extract_addresses(&self) -> Vec<Address> {
        self.into_iter()
            .filter_map(|e| {
                if let EntryValue::Address(address) = &e.value {
                    Some(address.clone())
                } else {
                    None
                }
            })
            .collect()
    }
}

pub async fn list_roots(db_executor: &Addr<crate::database::DbExecutor>) -> Result<Vec<Entry>> {
    let all_directories: Vec<Entry> = db_executor
        .send(QueryEntries {
            target: None,
            key: Some(DIR_KEY.to_string()),
            value: None,
        })
        .await??;

    let directories_with_parents: Vec<Address> = db_executor
        .send(QueryEntries {
            target: None,
            key: Some(DIR_HAS_KEY.to_string()),
            value: None,
        })
        .await??
        .extract_addresses();

    Ok(all_directories
        .into_iter()
        .filter(|entry| !directories_with_parents.contains(&entry.target))
        .collect())
}

pub async fn list_directory(db_executor: &Addr<DbExecutor>, path: &UPath) -> Result<Vec<Entry>> {
    let entry_addresses = match path.0.len() {
        0 => list_roots(db_executor)
            .await?
            .into_iter()
            .map(|e| e.target)
            .collect(),
        _ => {
            let resolved_path: Vec<Address> = resolve_path(db_executor, path, false).await?;
            let last = resolved_path.last().unwrap();

            db_executor
                .send(QueryEntries {
                    target: Some(last.clone()),
                    key: Some(DIR_HAS_KEY.to_string()),
                    value: None,
                })
                .await??
                .extract_addresses()
        }
    };

    let mut result: Vec<Entry> = vec![];
    for address in entry_addresses {
        result.extend(
            db_executor
                .send(RetrieveObject { target: address })
                .await??
                .into_iter()
                .filter(|e| [DIR_KEY, FILENAME_KEY, FILE_IDENTITY_KEY].contains(&e.key.as_str()))
                .collect::<Vec<Entry>>(),
        );
    }
    Ok(result)
}

pub async fn fetch_or_create_dir(
    db_executor: &Addr<crate::database::DbExecutor>,
    parent: Option<Address>,
    directory: UDirectory,
    create: bool,
) -> Result<Address> {
    match parent.clone() {
        Some(address) => trace!("FETCHING/CREATING {}/{:#}", address, directory),
        None => trace!("FETCHING/CREATING /{:#}", directory),
    }

    let dir_value = EntryValue::Value(Value::String(directory.name));
    let directories: Vec<Address> = db_executor
        .send(QueryEntries {
            target: None,
            key: Some(String::from(DIR_KEY)),
            value: Some(dir_value.clone()),
        })
        .await??
        .into_iter()
        .map(|e: Entry| e.target)
        .collect();

    let valid_directories: Vec<Address> = match parent.clone() {
        Some(address) => {
            let parent_has: Vec<Address> = db_executor
                .send(QueryEntries {
                    target: Some(address),
                    key: Some(String::from(DIR_HAS_KEY)),
                    value: None,
                })
                .await??
                .extract_addresses();

            let valid = directories
                .into_iter()
                .filter(|a| parent_has.contains(a))
                .collect();

            valid
        }
        None => directories,
    };

    match valid_directories.len() {
        0 => {
            if create {
                let new_directory_address = Address::UUID(Uuid::new_v4());
                let directory_entry = InnerEntry {
                    target: new_directory_address.clone(),
                    key: String::from(DIR_KEY),
                    value: dir_value,
                };
                let _ = db_executor
                    .send(InsertEntry {
                        entry: directory_entry,
                    })
                    .await??;

                if parent.is_some() {
                    let has_entry = InnerEntry {
                        target: parent.unwrap(),
                        key: String::from(DIR_HAS_KEY),
                        value: EntryValue::Address(new_directory_address.clone()),
                    };
                    let _ = db_executor.send(InsertEntry { entry: has_entry }).await??;
                }

                Ok(new_directory_address)
            } else {
                Err(anyhow!("Directory does not exist."))
            }
        }
        1 => Ok(valid_directories[0].clone()),
        _ => Err(anyhow!(
            "Invalid database state - more than one directory matches the query!"
        )),
    }
}

pub async fn resolve_path(
    db_executor: &Addr<DbExecutor>,
    path: &UPath,
    create: bool,
) -> Result<Vec<Address>> {
    let mut result: Vec<Address> = vec![];
    let mut path_stack = path.0.to_vec();

    path_stack.reverse();
    while path_stack.len() > 0 {
        let dir_address = fetch_or_create_dir(
            db_executor,
            result.last().cloned(),
            path_stack.pop().unwrap(),
            create,
        )
        .await?;
        result.push(dir_address);
    }

    Ok(result)
}

async fn _reimport_directory<T: AsRef<Path>>(
    directory: T,
    db_executor: &Addr<crate::database::DbExecutor>,
    hasher_worker: &Addr<HasherWorker>,
) -> Result<()> {
    for path in WalkDir::new(&directory)
        .into_iter()
        .filter_map(|e| e.ok())
        .filter(|e| e.path().is_file())
        .map(|e| e.into_path())
    {
        info!("Processing: {:?}", path);

        let metadata = fs::metadata(&path)?;
        let size = metadata.len() as i64;
        if size < 0 {
            panic!("File {} too large?!", path.display());
        }

        let digest = hasher_worker
            .send(ComputeHash {
                path: path.to_path_buf(),
            })
            .await??;

        let existing_file: Option<String> = db_executor
            .send(RetrieveByHash {
                hash: digest.clone(),
            })
            .await??;

        if existing_file.is_none() {
            let new_file = models::NewFile {
                path: path.to_str().expect("path not valid unicode?!").to_string(),
                hash: (digest.clone()).0,
                created: NaiveDateTime::from_timestamp(Utc::now().timestamp(), 0),
                size,
            };

            db_executor
                .send(crate::database::InsertFile { file: new_file })
                .await??;
        }

        let components = path.components().collect::<Vec<Component>>();
        let (filename, dir_path) = components.split_last().unwrap();

        let file_address = Address::UUID(Uuid::new_v4());

        let name_entry = InnerEntry {
            target: file_address.clone(),
            key: FILENAME_KEY.to_string(),
            value: EntryValue::Value(Value::String(
                filename.as_os_str().to_string_lossy().to_string(),
            )),
        };
        db_executor
            .send(crate::database::InsertEntry { entry: name_entry })
            .await??;

        let identity_entry = InnerEntry {
            target: file_address.clone(),
            key: FILE_IDENTITY_KEY.to_string(),
            value: EntryValue::Address(Address::Hash(digest.clone())),
        };
        db_executor
            .send(crate::database::InsertEntry {
                entry: identity_entry,
            })
            .await??;

        let upath = UPath(
            iter::once(UDirectory {
                name: "NATIVE".to_string(),
            })
            .chain(dir_path.iter().map(|component| UDirectory {
                name: component.as_os_str().to_string_lossy().to_string(),
            }))
            .collect(),
        );
        let resolved_path = resolve_path(db_executor, &upath, true).await?;
        let parent_dir = resolved_path.last().unwrap();
        let dir_has_entry = InnerEntry {
            target: parent_dir.clone(),
            key: DIR_HAS_KEY.to_string(),
            value: EntryValue::Address(file_address),
        };
        db_executor
            .send(crate::database::InsertEntry {
                entry: dir_has_entry,
            })
            .await??;
    }
    info!("Finished updating {}.", directory.as_ref().display());

    Ok(())
}

pub async fn reimport_directory(
    directory: PathBuf,
    db_executor: Addr<crate::database::DbExecutor>,
    hasher_worker: Addr<HasherWorker>,
) {
    let result = _reimport_directory(directory, &db_executor, &hasher_worker).await;
    if result.is_err() {
        warn!("Update did not succeed! {}", result.err().unwrap());
    }
}

#[cfg(test)]
mod tests {
    use crate::filesystem::{UDirectory, UPath};
    use anyhow::Result;

    #[test]
    fn test_path_codec() {
        let path = UPath(vec![
            UDirectory {
                name: "top".to_string(),
            },
            UDirectory {
                name: "foo".to_string(),
            },
            UDirectory {
                name: "bar".to_string(),
            },
            UDirectory {
                name: "baz".to_string(),
            },
        ]);

        let str_path = path.to_string();
        assert!(str_path.len() > 0);

        let decoded_path: Result<UPath> = str_path.parse();
        assert!(decoded_path.is_ok());

        assert_eq!(path, decoded_path.unwrap());
    }

    #[test]
    fn test_validation() {
        let invalid_path: Result<UPath> = "a//b/c//d/e/f///g".parse();
        assert!(invalid_path.is_err())
    }
}