use std::{collections::HashMap, path::PathBuf};

use cfg_file::{ConfigFile, config::ConfigFile};
use serde::{Deserialize, Serialize};
use string_proc::simple_processer::sanitize_file_path;

use crate::{
    constants::SERVER_FILE_SHEET,
    data::{
        member::MemberId,
        vault::{Vault, virtual_file::VirtualFileId},
    },
};

pub type SheetName = String;
pub type SheetPathBuf = PathBuf;
pub type InputName = String;
pub type InputRelativePathBuf = PathBuf;

#[derive(Debug, Clone, Serialize, Deserialize, Eq)]
pub struct InputPackage {
    /// Name of the input package
    pub name: InputName,

    /// The sheet from which this input package was created
    pub from: SheetName,

    /// Files in this input package with their relative paths and virtual file IDs
    pub files: Vec<(InputRelativePathBuf, VirtualFileId)>,
}

impl PartialEq for InputPackage {
    fn eq(&self, other: &Self) -> bool {
        self.name == other.name
    }
}

const SHEET_NAME: &str = "{sheet-name}";

pub struct Sheet<'a> {
    /// The name of the current sheet
    pub(crate) name: SheetName,

    /// Sheet data
    pub(crate) data: SheetData,

    /// Sheet path
    pub(crate) vault_reference: &'a Vault,
}

#[derive(Default, Serialize, Deserialize, ConfigFile)]
pub struct SheetData {
    /// The holder of the current sheet, who has full operation rights to the sheet mapping
    pub(crate) holder: MemberId,

    /// Inputs
    pub(crate) inputs: Vec<InputPackage>,

    /// Mapping of sheet paths to virtual file IDs
    pub(crate) mapping: HashMap<SheetPathBuf, VirtualFileId>,
}

impl<'a> Sheet<'a> {
    /// Get the holder of this sheet
    pub fn holder(&self) -> &MemberId {
        &self.data.holder
    }

    /// Get the inputs of this sheet
    pub fn inputs(&self) -> &Vec<InputPackage> {
        &self.data.inputs
    }

    /// Get the mapping of this sheet
    pub fn mapping(&self) -> &HashMap<SheetPathBuf, VirtualFileId> {
        &self.data.mapping
    }

    /// Add an input package to the sheet
    pub fn add_input(&mut self, input_package: InputPackage) -> Result<(), std::io::Error> {
        if self.data.inputs.iter().any(|input| input == &input_package) {
            return Err(std::io::Error::new(
                std::io::ErrorKind::AlreadyExists,
                format!("Input package '{}' already exists", input_package.name),
            ));
        }
        self.data.inputs.push(input_package);
        Ok(())
    }

    /// Remove an input package from the sheet
    pub fn remove_input(&mut self, input_name: &InputName) -> Option<InputPackage> {
        self.data
            .inputs
            .iter()
            .position(|input| input.name == *input_name)
            .map(|pos| self.data.inputs.remove(pos))
    }

    /// Add a mapping entry to the sheet
    pub fn add_mapping(&mut self, sheet_path: SheetPathBuf, virtual_file_id: VirtualFileId) {
        self.data.mapping.insert(sheet_path, virtual_file_id);
    }

    /// Remove a mapping entry from the sheet
    pub fn remove_mapping(&mut self, sheet_path: &SheetPathBuf) -> Option<VirtualFileId> {
        self.data.mapping.remove(sheet_path)
    }

    /// Persist the sheet to disk
    ///
    /// Why not use a reference?
    /// Because I don't want a second instance of the sheet to be kept in memory.
    /// If needed, please deserialize and reload it.
    pub async fn persist(self) -> Result<(), std::io::Error> {
        SheetData::write_to(&self.data, self.sheet_path()).await
    }

    /// Get the path to the sheet file
    pub fn sheet_path(&self) -> PathBuf {
        Sheet::sheet_path_with_name(self.vault_reference, &self.name)
    }

    /// Get the path to the sheet file with the given name
    pub fn sheet_path_with_name(vault: &Vault, name: impl AsRef<str>) -> PathBuf {
        vault
            .vault_path()
            .join(SERVER_FILE_SHEET.replace(SHEET_NAME, name.as_ref()))
    }

    /// Export files from the current sheet as an InputPackage for importing into other sheets
    ///
    /// This is the recommended way to create InputPackages. It takes a list of sheet paths
    /// and generates an InputPackage with optimized relative paths by removing the longest
    /// common prefix from all provided paths, then placing the files under a directory
    /// named with the output_name.
    ///
    /// # Example
    /// Given paths:
    /// - `MyProject/Art/Character/Model/final.fbx`
    /// - `MyProject/Art/Character/Texture/final.png`
    /// - `MyProject/Art/Character/README.md`
    ///
    /// With output_name = "MyExport", the resulting package will contain:
    /// - `MyExport/Model/final.fbx`
    /// - `MyExport/Texture/final.png`
    /// - `MyExport/README.md`
    ///
    /// # Arguments
    /// * `output_name` - Name of the output package (will be used as the root directory)
    /// * `paths` - List of sheet paths to include in the package
    ///
    /// # Returns
    /// Returns an InputPackage containing the exported files with optimized paths,
    /// or an error if paths are empty or files are not found in the sheet mapping
    pub fn output_mappings(
        &self,
        output_name: InputName,
        paths: &[SheetPathBuf],
    ) -> Result<InputPackage, std::io::Error> {
        let output_name = sanitize_file_path(output_name);

        // Return error for empty paths since there's no need to generate an empty package
        if paths.is_empty() {
            return Err(std::io::Error::new(
                std::io::ErrorKind::InvalidInput,
                "Cannot generate output package with empty paths",
            ));
        }

        // Find the longest common prefix among all paths
        let common_prefix = paths.iter().skip(1).fold(paths[0].clone(), |prefix, path| {
            Self::common_path_prefix(prefix, path)
        });

        // Create output files with optimized relative paths
        let files = paths
            .iter()
            .map(|path| {
                let relative_path = path.strip_prefix(&common_prefix).unwrap_or(path);
                let output_path = PathBuf::from(&output_name).join(relative_path);

                self.data
                    .mapping
                    .get(path)
                    .map(|vfid| (output_path, vfid.clone()))
                    .ok_or_else(|| {
                        std::io::Error::new(
                            std::io::ErrorKind::NotFound,
                            format!("File not found: {:?}", path),
                        )
                    })
            })
            .collect::<Result<Vec<_>, _>>()?;

        Ok(InputPackage {
            name: output_name,
            from: self.name.clone(),
            files,
        })
    }

    /// Helper function to find common path prefix between two paths
    fn common_path_prefix(path1: impl Into<PathBuf>, path2: impl Into<PathBuf>) -> PathBuf {
        let path1 = path1.into();
        let path2 = path2.into();

        path1
            .components()
            .zip(path2.components())
            .take_while(|(a, b)| a == b)
            .map(|(comp, _)| comp)
            .collect()
    }
}