use crate::types::{CadeActions, Env, EnvSet, InnerHook};
use anyhow::{Context, Result, anyhow, bail};
use std::{
    collections::HashMap,
    ffi::OsString,
    fmt::{Debug, Display},
    io::{BufRead, Read},
    path::{Path, PathBuf},
};

#[repr(u8)]
#[derive(bincode::Encode, bincode::Decode, PartialEq, Debug)]
pub enum Permission {
    Allowed,
    Disallowed,
}

impl Display for Permission {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        Debug::fmt(self, f)
    }
}

pub fn load_flake(path: &Path, output: Option<String>) -> Result<RawEnv> {
    let mut nix_cmd = String::from("nix print-dev-env --json");
    if let Some(flake_output) = output {
        nix_cmd.push_str(&[" ", &flake_output, " "].concat());
    }
    let mut proc = std::process::Command::new("sh");
    // proc.env_clear();
    proc.arg("-c");
    proc.arg(nix_cmd);
    proc.current_dir(path);
    let output = proc
        .output()
        .with_context(|| format!("loading flake at {}", path.display()))?
        .stdout;
    parse_json(output)
}

pub fn load_shell(path: &Path, filename: String) -> Result<RawEnv> {
    let mut nix_cmd = String::from("nix print-dev-env --json ");
    // let mut nix_cmd = String::from("nix-shell ");
    if !filename.is_empty() {
        nix_cmd.push_str(&["-F ", &filename].concat());
    } else {
        nix_cmd.push_str(&["-F ./shell.nix"].concat());
    }
    // nix_cmd.push_str("--pure --command env --null");
    let mut proc = std::process::Command::new("sh");
    proc.env_clear();
    proc.arg("-c");
    proc.arg(nix_cmd);
    proc.current_dir(path);
    let output = proc
        .output()
        .with_context(|| format!("loading shell at {}", path.display()))?
        .stdout;
    EnvSet::from_json(output)?
}

pub fn load_env(path: &Path, filename: String) -> Result<EnvSet> {
    let mut p = path.to_path_buf();
    if filename.is_empty() {
        p.push(".env");
    } else {
        p.push(filename);
    }
    let mut file = std::fs::File::open(p)
        .with_context(|| format!("opening env file at {}", path.display()))?;
    let mut buf = String::new();
    file.read_to_string(&mut buf).context("reading env file")?;
    parse_envs(buf)
}

pub fn call(path: &Path, argv: Vec<String>) -> Result<EnvSet> {
    let mut it = argv.iter();
    // safety: already checked at parsing
    let mut process = std::process::Command::new(it.next().unwrap());
    process.current_dir(path);
    process.args(it);
    let output = process
        .output()
        .with_context(|| format!("running process {}", argv.concat()))?
        .stdout;

    let text = String::from_utf8(output)
        .with_context(|| format!("converting call {} output to text", argv.concat()))?
        .replace(' ', "\0");
    parse_envs(text)
}

// TODO cache results by hash/storepath and read from db so we don't
// need to eat eval every time

fn check_permission(dir: &Path) -> Permission {
    // TODO check database for permission
    todo!();
}

pub fn do_activation() -> Result<()> {
    let dir = ensure_dir()?;
    // TODO finish sqlite impl
    let db = rusqlite::Connection::open(dir)?;

    // let db = sled::open(dir).context("open database")?;
    let mut cwd = std::env::current_dir().context("determine CWD")?;
    let cwd_str = cwd
        .clone()
        .into_os_string()
        .into_string()
        .map_err(|_| anyhow!("cwd has invalid unicode"))?;

    let permission = db.query_one(
        "SELECT Permission FROM WorkingPaths WHERE Path=(:path)",
        &[(":path", &cwd_str)],
        |row| Ok(row.get(0).unwrap_or(false)),
    )?;
    if !permission {
        bail!("cade is not permitted to operate here; use 'cade allow'.");
    }

    let base_env = std::env::vars().collect::<HashMap<String, String>>();

    use crate::core::{read_cade, realise};
    let mut cascade = HashMap::new();
    cascade.insert(
        cwd.clone(),
        read_cade(&cwd.join(".cade")).context("reading cade file")?,
    );

    // recurse into parent dirs
    while let Some(parent) = cwd.parent()
        && std::fs::exists(parent.join(".cade"))
            .context("check for .cade file in parent directory")?
    {
        cwd = parent.to_path_buf();
        cascade.insert(
            cwd.clone(),
            read_cade(&cwd.join(".cade")).context("reading cade file")?,
        );
    }

    let mut env = HashMap::new();
    let adjustments = realise(cascade)?;
    use CadeActions::*;
    for action in adjustments {
        match action {
            Environ(env_actions) => {
                for action in env_actions {
                    env.entry(action.name)
                        .and_modify(|iv: &mut Vec<String>| {
                            iv.extend(action.value.clone());
                        })
                        .or_insert(action.value);
                }
            }
            Purify => {
                // FIXME this is a dumb way to purify an env
                for (bk, bv) in base_env.iter() {
                    if env.get(bk).is_some_and(|inner| inner.contains(bv)) {
                        env.remove(bk);
                    }
                }
            }
            Hook(hook) => match hook.kind {
                _ => todo!(),
            },
        };
    }
    for (k, v) in env {
        let value: String = v.into_iter().map(|s| [&s, ":"].concat()).collect();
        println!("{k}={}", &value[..value.len() - 1]);
    }
    Ok(())
}

pub fn set_permission(permission: Permission) -> Result<()> {
    let dir = ensure_dir()?;
    let db = sled::open(dir).context("open database")?;
    let cwd = std::env::current_dir()
        .context("determine CWD")?
        .into_os_string();
    let encoded_permission = bincode::encode_to_vec(&permission, bincode::config::standard())
        .context("encode permission value")?;

    let _ = db
        .insert(cwd.into_encoded_bytes(), encoded_permission)
        .context("update permissions database")?;
    eprintln!(
        "cade is now {} here.",
        permission.to_string().to_lowercase()
    );
    Ok(())
}

fn ensure_dir() -> Result<PathBuf> {
    let xdg = microxdg::Xdg::new().context("establish XDG paths")?;
    let mut path = xdg.state().context("find xdg state dir")?;
    path.push("cade");
    if !std::fs::exists(&path).is_ok_and(|v| v) {
        std::fs::create_dir(&path).context("create cade's state path")?;
    }
    // FIXME should this be appended after ? we only guarantee the dir here ..
    path.push("permissions.db");
    Ok(path)
}