// This file is part of bsv.
//
// bsv is free software: you can redistribute it and/or modify it under the
// terms of the GNU Affero General Public License as published by the Free
// Software Foundation, either version 3 of the License, or (at your option)
// any later version.
//
// bsv is distributed in the hope that it will be useful, but WITHOUT ANY
// WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
// FOR A PARTICULAR PURPOSE.  See the GNU Affero General Public License for
// more details.
//
// You should have received a copy of the Affero GNU General Public License
// along with bsv.  If not, see <https://www.gnu.org/licenses/>.


use std::{fs::create_dir_all, io::BufReader};

use camino::{Utf8Path, Utf8PathBuf};
use cas_simple::utils::config_path;
use toml::{Value, Table};

use cas_core::{err, Error, ObjectId, Result, ObjectType, CasWithRef};
use cas_simple::{SimpleCas, SimpleCasConfig};

use crate::PathMap;
pub use crate::permissions::Permissions;
use crate::tree_item::Deserialize;
pub use crate::tree_item::{Serialize, TreeItem};


#[derive(Clone, Debug)]
pub struct Config {
    pub device_name: String,
    pub cas: SimpleCasConfig,
    pub path_map: PathMap,
}

impl Config {
    pub fn from_toml_value(value: &Value) -> Result<Self> {
        let bsv_value = value.get("bsv")
            .ok_or_else(|| Error::unknown("bsv section missing from config"))?;
        if !bsv_value.is_table() {
            return err!("bsv section must be a table");
        }

        Ok(Self {
            device_name: bsv_value.get("device_name")
                .ok_or_else(|| Error::unknown("bsv.device_name missing from config"))?
                .as_str()
                .ok_or_else(|| Error::unknown("bsv.device_name must be a string"))?
                .to_string(),
            cas: SimpleCasConfig::from_toml_value(
                value.get("cas").ok_or_else(|| Error::unknown("config must have a cas section"))?
            )?,
            path_map: PathMap::from_toml_value(
                value.get("mapping").ok_or_else(|| Error::unknown("config must have a mapping section"))?
            )?,
        })
    }

    pub fn from_toml_file(config_path: &Utf8Path) -> Result<Self> {
        use std::io::Read;

        let mut file = std::fs::File::open(config_path).or_else(|err|
            err!("invalid repository: failed to read config file: {}", err)
        )?;
        let mut config_str = String::new();
        file.read_to_string(&mut config_str).or_else(|err|
            err!("failed to read config file: {}", err)
        )?;
        let value = config_str.parse::<Value>().or_else(|err|
            err!("parse error while reading config file: {}", err)
        )?;
        Self::from_toml_value(&value)
    }

    pub fn to_toml_value(&self) -> Result<Value> {
        let mut bsv = Table::new();
        bsv["device_name"] = Value::String(self.device_name.clone());

        let mut table = Table::new();
        table["bsv"] = Value::Table(bsv);
        table["cas"] = self.cas.to_toml_value()?;
        table["mapping"] = self.path_map.to_toml_value()?;

        Ok(Value::Table(table))
    }

    pub fn write_toml_file(&self, config_path: &Utf8Path) -> Result<()> {
        use std::io::Write;

        let value = self.to_toml_value()?;
        let config_str = toml::to_string_pretty(&value).or_else(|err|
            err!("failed to serialize config: {}", err)
        )?;
        let mut file = tempfile::NamedTempFile::new_in(config_path.parent().unwrap()).or_else(|err|
            err!("cannot create temp config file: {}", err)
        )?;
        file.write_all(config_str.as_bytes()).or_else(|err|
            err!("failed to write to temp config: {}", err)
        )?;
        file.persist(config_path).or_else(|err|
            err!("failed to (over)write config: {}", err)
        )?;
        Ok(())
    }
}


pub struct Repository {
    config: Config,
    cas: Box<dyn CasWithRef>,
}

impl Repository {
    pub fn create(path: Utf8PathBuf, config: Config) -> Result<Self> {
        if path.exists() {
            return err!("cannot create bsv repository, path {} already exists", path);
        }

        create_dir_all(&path)?;
        config.write_toml_file(&config_path(&path))?;
        let cas = SimpleCas::create(path.to_path_buf(), config.cas.clone())?;

        Ok(Self {
            config,
            cas: Box::new(cas),
        })
    }

    pub fn open(path: Utf8PathBuf) -> Result<Self> {
        if !path.is_dir() {
            return err!("failed to open repository, path {} is not a directory", path);
        }

        let config_file = cas_simple::utils::config_path(&path);
        let config = Config::from_toml_file(&config_file)?;

        let cas = SimpleCas::open(path, config.cas.clone())?;

        Ok(Self {
            config,
            cas: Box::new(cas),
        })
    }

    pub fn cas(&self) -> &dyn CasWithRef {
        self.cas.as_ref()
    }

    pub fn physic_from_logic_path<P: AsRef<Utf8Path>>(&self, logic_path: P) -> Option<Utf8PathBuf> {
        self.config.path_map.physic_from_logic(&logic_path)
    }

    pub fn path_pair_from_physic_path<P: AsRef<Utf8Path>>(&self, physic_path: P) -> Option<Utf8PathBuf> {
        self.config.path_map.logic_from_physic(&physic_path)
    }

    pub fn oid_from_logic_path<P: AsRef<Utf8Path>>(&self, _logic_path: P) -> Result<ObjectId> {
        // let snapshot_oid = self.cas.get_ref(Utf8Path::new("latest"))?;
        // let snapshot = self.read_snapshot(snapshot_oid)?;
        err!("not implemented")
    }

    pub fn oid_from_physic_path<P: AsRef<Utf8Path>>(&self, physic_path: P) -> Result<ObjectId> {
        let logic_path = self.config.path_map.logic_from_physic(physic_path)
            .ok_or_else(|| Error::unknown("physic path do not map to a logic path"))?;
        self.oid_from_logic_path(logic_path)
    }

    pub fn read_tree(&self, oid: &ObjectId) -> Result<Option<Vec<TreeItem>>> {
        match self.cas.open_object(oid) {
            Ok((metadata, mut reader)) => {
                if metadata.otype() != &ObjectType::new(b"tree")? {
                    err!("object is not a tree")
                }
                else {
                    let mut buf_read = BufReader::new(reader.as_mut());
                    Ok(Some(
                        Vec::<TreeItem>::deserialize(&mut buf_read)?
                        .unwrap_or_else(|| Vec::new())
                    ))
                }
            },
            Err(Error::ObjectDoesNotExists(_)) => {
                Ok(None)
            }
            Err(err) => {
                Err(err)
            }
        }
    }

    // pub fn add<P, V>(&mut self, path: P, visitor: &mut V) -> Result<ObjectId>
    //     where
    //         P: AsRef<Utf8Path>,
    //         V: FsVisitor,
    // {
    //     let path_ref = path.as_ref();
    //     let metadata = std::fs::symlink_metadata(path_ref)
    //         .or_else(|err| err!("failed to read file {}: {}", path_ref, err))?;

    //     if visitor.accept(path_ref, &metadata) {
    //         self.add_impl(path_ref, &metadata, visitor)
    //     }
    //     else {
    //         err!("cannot add {}: path is excluded", path_ref)
    //     }
    // }

    // pub fn add_impl<V>(&mut self, path: &Utf8Path, metadata: &Metadata, visitor: &mut V) -> Result<ObjectId>
    //     where
    //         V: FsVisitor,
    // {
    //     let file_type = metadata.file_type();

    //     if file_type.is_file() {
    //         self.add_file(path, metadata)
    //     }
    //     else if file_type.is_dir() {
    //         self.add_tree(path, metadata, visitor)
    //     }
    //     else if file_type.is_symlink() {
    //         err!("symlink are not supported yet")
    //     }
    //     else {
    //         err!("not implemented")
    //     }
    // }

    // pub fn add_tree_item<V>(&mut self, path: &Utf8Path, metadata: &Metadata, visitor: &mut V) -> Result<TreeItem>
    //     where
    //         V: FsVisitor,
    // {
    //     let item_name = path
    //         .file_name()
    //         .ok_or_else(|| Error::unknown("dir entry with no name?"))?
    //         .to_str()
    //         .ok_or_else(|| Error::unknown(format!("file name contains non-unicode characters: {}", path)))?;

    //     let oid = self.add(&path, visitor)?;

    //     TreeItem::from_metadata(
    //         item_name,
    //         &metadata,
    //         oid,
    //     )
    // }

    // fn add_file(&mut self, path: &Utf8Path, metadata: &Metadata) -> Result<ObjectId> {
    //     if !metadata.is_file() {
    //         return err!("expected file");
    //     }

    //     let file_size = metadata.len();

    //     let mut reader = std::fs::File::open(path)
    //         .or_else(|err| err!("failed to open file {}: {}", path, err))?;

    //     let mut writer = self.cas.new_writer(
    //         &ObjectType::new(b"blob")?,
    //         file_size
    //     )?;

    //     let mut buffer = [0; BUFFER_SIZE];
    //     let mut byte_count = 0u64;
    //     loop {
    //         use std::io::{Read, Write};
    //         let count = reader.read(&mut buffer)
    //             .or_else(|err| err!("error while reading {}: {}", path, err))?;
    //         if count == 0 {
    //             break;
    //         }
    //         byte_count += count as u64;
    //         writer.write_all(&buffer[..count])
    //             .or_else(|err| err!("error while writing blob for {}: {}", path, err))?;
    //     }

    //     if byte_count == file_size {
    //         writer.finalize()
    //     }
    //     else {
    //         err!("file size changed during processing for {}", path)
    //     }
    // }

    // fn add_tree<V>(&mut self, path: &Utf8Path, metadata: &Metadata, visitor: &mut V) -> Result<ObjectId>
    //     where
    //         V: FsVisitor,
    // {
    //     if !metadata.is_dir() {
    //         return err!("expected directory");
    //     }

    //     let mut tree = std::fs::read_dir(path)
    //         .or_else(|err| err!("error while reading dir {}: {}", path, err))?
    //         .filter_map(|entry| self.add_dir_entry(path, entry, visitor))
    //         .collect::<Result<Vec<_>>>()?;

    //     tree.sort_unstable_by(|item0, item1| item0.name.cmp(&item1.name));

    //     let mut out = Vec::new();
    //     tree.serialize(&mut out)?;
    //     self.cas.write_object(
    //         &ObjectType::new(b"tree")?,
    //         &out,
    //     )
    // }

    // fn add_dir_entry<V>(&mut self, dir_path: &Utf8Path, entry: std::io::Result<std::fs::DirEntry>, visitor: &mut V) -> Option<Result<TreeItem>>
    //     where
    //         V: FsVisitor
    // {
    //     let (entry_path, metadata) = match visitor.handle_result(Self::dir_entry_path_metadata(dir_path, entry)) {
    //         Ok(path_metadata) => { path_metadata },
    //         Err(error)        => { return Some(Err(error)) }
    //     };

    //     if visitor.accept(&entry_path, &metadata) {
    //         let result = self.add_tree_item(&entry_path, &metadata, visitor);
    //         Some(visitor.handle_result(result))
    //     }
    //     else {
    //         None
    //     }
    // }

    // fn dir_entry_path_metadata(dir_path: &Utf8Path, entry: std::io::Result<std::fs::DirEntry>) -> Result<(Utf8PathBuf, Metadata)> {
    //     let dir_entry = entry
    //         .or_else(|err| err!("error while reading dir {}: {}", dir_path, err))?;

    //     let entry_path = dir_entry.path();
    //     let metadata = dir_entry.metadata()
    //         .or_else(|err| err!("failed to read metadata for dir entry {}: {}", entry_path, err))?;

    //     Ok((entry_path, metadata))
    // }
}