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

use globset::{Glob, GlobSet, GlobSetBuilder};
use log::{debug, trace, warn};
use thiserror::Error;

use crate::{
    file_conflict_solver::ConflictSolver,
    fomod, install_prompt,
    mod_config_installer::run_fomod_installer,
    types::{InstalledMod, ModConfig, ModFile, ModdedInstance, RootConfig},
    utils::{resolve_case_insensitive, walk_all_files},
};

pub fn insert_mod_to_instance(
    instance: &mut ModdedInstance,
    from_mod: &ModConfig,
    files: &[ModFile],
    priority: isize,
) -> Result<(), InststanceError> {
    let mut solver = ConflictSolver::new();

    let mut installed_files: Vec<(ModFile, &InstalledMod)> = Vec::new();
    for installed_mod in instance.mods() {
        for link in installed_mod.files() {
            let recreated_mod_file = ModFile::new(link.src(), link.dst(), 0);
            installed_files.push((recreated_mod_file, installed_mod));
        }
    }

    for (file, from_mod) in &installed_files {
        if let Some(conflict) = solver.add_file(file, from_mod) {
            warn!("File conflict on already added file: {:?}", conflict);
        }
    }

    let new_mod = InstalledMod::new(from_mod.id(), priority);
    for file in files {
        if let Some(conflict) = solver.add_file(file, &new_mod) {
            return Err(InststanceError::FileConflict {
                lhs_mod_id: conflict.lhs_mod.mod_id().to_owned(),
                rhs_mod_id: conflict.rhs_mod.mod_id().to_owned(),
                path: conflict.rhs_file.dst().to_owned(),
            });
        }
    }

    let new_link_tree = solver.export_files();

    let mut map: HashMap<String, InstalledMod> = HashMap::new();

    for (file, from_mod) in new_link_tree {
        match map.get_mut(from_mod.mod_id()) {
            Some(existing) => {
                existing.add_file(file);
            }
            None => {
                let mut new_mod = InstalledMod::new(from_mod.mod_id(), from_mod.priority());
                new_mod.add_file(file);
                map.insert(new_mod.mod_id().to_owned(), new_mod);
            }
        }
    }

    for (_, installed_mod) in map {
        instance.update_or_create_mod(&installed_mod);
    }

    Ok(())
}

pub fn files_to_install_mod(
    root_config: &RootConfig,
    instance: &ModdedInstance,
    mod_to_install: &ModConfig,
) -> anyhow::Result<Vec<ModFile>> {
    let mod_location = root_config.mod_location().join(mod_to_install.path());

    let files = match determain_mod_kind(mod_to_install, &mod_location)? {
        ModKind::Fomod(xml_path) => install_fomod(instance, xml_path, &mod_location)?,
        ModKind::EmbeddedData(data_path) => {
            install_from_dir(mod_to_install, mod_location.join(data_path))?
        }
        ModKind::Root => install_from_dir(mod_to_install, mod_location)?,
        ModKind::Unkown => install_from_dir_to_data(mod_to_install, mod_location)?,
    };

    Ok(files)
}

fn determain_mod_kind(
    mod_config: &ModConfig,
    mod_location: impl AsRef<Path>,
) -> Result<ModKind, io::Error> {
    if mod_config.is_root_mod() {
        return Ok(ModKind::Root);
    }

    // Check for moduleconfig.xml
    let module_config_path = resolve_case_insensitive(&mod_location, "fomod/ModuleConfig.xml")?;

    if let Some(path) = module_config_path {
        return Ok(ModKind::Fomod(path));
    };

    match resolve_case_insensitive(&mod_location, "data")? {
        Some(data_path) => Ok(ModKind::EmbeddedData(data_path)),
        None => Ok(ModKind::Unkown),
    }
}

fn install_fomod(
    instance: &ModdedInstance,
    module_config_path: impl AsRef<Path>,
    mod_root: impl AsRef<Path>,
) -> anyhow::Result<Vec<ModFile>> {
    debug!("Running FOmod installer");
    let module_config = fomod::Config::load_from_file(module_config_path)?;

    let active_plugins: Vec<_> = instance
        .active_plugins()
        .map(|e| e.to_string_lossy())
        .map(|e| e.to_string())
        .collect();

    trace!("Current loded plugins: {:?}", active_plugins);
    let files = run_fomod_installer(module_config, &active_plugins, install_prompt::prompt)
        .map_err(|_| InststanceError::FomodRunInstaller)?;

    let mod_files: Vec<_> = files
        .iter()
        .map(|f| {
            ModFile::from_installer(f.clone(), &mod_root).map_err(InststanceError::FomodFinalize)
        })
        .collect::<Result<Vec<_>, _>>()?
        .into_iter()
        .flatten()
        .collect();
    Ok(mod_files)
}

fn install_from_dir(
    mod_config: &ModConfig,
    mod_location: impl AsRef<Path>,
) -> anyhow::Result<Vec<ModFile>> {
    let glob_filter = create_glob_filter(mod_config.ignore())?;

    let files: Vec<_> = walk_all_files(&mod_location)?
        .map(|entry| entry.path().strip_prefix(&mod_location).unwrap().to_owned())
        .filter(|rel_path| !glob_filter.is_match(rel_path))
        .map(|rel_path| ModFile::new(&rel_path, &rel_path, 0))
        .collect();

    Ok(files)
}

fn install_from_dir_to_data(
    mod_config: &ModConfig,
    path: impl AsRef<Path>,
) -> anyhow::Result<Vec<ModFile>> {
    let glob_filter = create_glob_filter(mod_config.ignore())?;
    let data = PathBuf::from("Data");
    let files: Vec<ModFile> = walk_all_files(&path)?
        .map(|entry| entry.path().strip_prefix(&path).unwrap().to_owned())
        .filter(|rel_path| !glob_filter.is_match(rel_path))
        .filter(|rel_path| should_be_included(rel_path))
        .map(|rel_path| ModFile::new(&rel_path, data.join(&rel_path), 0))
        .collect();

    Ok(files)
}

fn create_glob_filter(rules: &[String]) -> anyhow::Result<GlobSet> {
    let mut builder = GlobSetBuilder::new();

    for p in rules {
        builder.add(Glob::new(p)?);
    }

    let set = builder.build()?;
    Ok(set)
}

enum ModKind {
    Fomod(PathBuf),
    EmbeddedData(PathBuf),
    Root,
    Unkown,
}

fn should_be_included(path: impl AsRef<Path>) -> bool {
    matches!(
        path.as_ref().extension().and_then(|e| e.to_str()),
        Some(
            "esp"
                | "esm"
                | "esl"
                | "bsa"
                | "ba2"
                | "bsl"
                | "ini"
                | "pex"
                | "psc"
                | "strings"
                | "ilstrings"
                | "dlstrings"
                | "dll"
        )
    )
}

#[derive(Debug, Error)]
pub enum InststanceError {
    #[error("Two mods write the same file")]
    FileConflict {
        lhs_mod_id: String,
        rhs_mod_id: String,
        path: PathBuf,
    },

    #[error("Failed to run fomod installer")]
    FomodRunInstaller,

    #[error("Failed to handle results of fomod installer")]
    FomodFinalize(io::Error),
}