// Copyright (C) 2026 Doan Luu Duc Tai <doan@luuduct.ai>
//
// This program 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.
//
// This program 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 GNU Affero General Public License
// along with this program.  If not, see <https://www.gnu.org/licenses/>.

use std::collections::BTreeMap;
use std::env;
use std::fs::{self, File, OpenOptions, Permissions};
use std::io::Read;
use std::os::unix::fs::{OpenOptionsExt, PermissionsExt};
use std::path::{Component, Path, PathBuf};
use std::process::Command;
use std::time::Duration;

use anyhow::{Context, Result, bail, ensure};
use serde::{Deserialize, Serialize};
use serde_json::Value;

use crate::{files, process};

#[derive(Clone, Copy, Debug, Default, Deserialize, Eq, PartialEq, Serialize)]
#[serde(rename_all = "lowercase")]
pub(crate) enum Mode {
    #[default]
    Local,
    Production,
}

#[derive(Debug, Deserialize, Serialize)]
#[serde(deny_unknown_fields)]
pub(crate) struct Settings {
    pub(crate) mode: Mode,
    pub(crate) port: u16,
    pub(crate) project: String,
    #[serde(default)]
    pub(crate) online: bool,
}

#[derive(Debug, Deserialize, Serialize)]
#[serde(deny_unknown_fields)]
pub(crate) struct Configuration {
    pub(crate) format: u32,
    pub(crate) services: BTreeMap<String, Service>,
}

#[derive(Debug, Deserialize, Serialize)]
#[serde(deny_unknown_fields)]
pub(crate) struct Service {
    pub(crate) image: String,
    pub(crate) build: Option<String>,
    #[serde(default)]
    gateway: bool,
    #[serde(default)]
    environment: Vec<String>,
    #[serde(default)]
    drop_capabilities: bool,
    health: Vec<String>,
    mounts: Vec<Mount>,
    #[serde(default)]
    tmpfs: Vec<String>,
}

#[derive(Debug, Deserialize, Serialize)]
#[serde(deny_unknown_fields)]
struct Mount {
    source: String,
    target: String,
    #[serde(default)]
    read_only: bool,
}

#[derive(Debug)]
pub(crate) struct Project {
    pub(crate) root: PathBuf,
}

impl Project {
    pub(crate) fn discover(explicit: Option<&Path>) -> Result<Self> {
        if let Some(path) = explicit {
            return Self::at(path);
        }
        let current = env::current_dir()?;
        for candidate in current.ancestors() {
            if candidate.join("infra/services.toml").is_file() {
                return Self::at(candidate);
            }
        }
        let executable = env::current_exe()?;
        for candidate in executable.ancestors().skip(1).take(3) {
            if candidate.join("infra/services.toml").is_file() {
                return Self::at(candidate);
            }
        }
        bail!("Run from the stack directory or supply --root PATH")
    }

    pub(crate) fn at(path: &Path) -> Result<Self> {
        let root = if path.is_absolute() {
            path.to_path_buf()
        } else {
            env::current_dir()?.join(path)
        };
        Ok(Self { root })
    }

    pub(crate) fn settings(&self) -> Result<Settings> {
        let path = self.root.join("var/state.json");
        if path.exists() {
            return Ok(serde_json::from_reader(File::open(path)?)?);
        }
        Ok(Settings {
            mode: Mode::Local,
            port: 8080,
            project: format!(
                "stack-{}",
                files::hash_bytes(self.root.as_os_str().as_encoded_bytes())
                    .chars()
                    .take(10)
                    .collect::<String>()
            ),
            online: false,
        })
    }

    pub(crate) fn save(&self, settings: &Settings) -> Result<()> {
        files::write(
            &self.root.join("var/state.json"),
            &serde_json::to_vec_pretty(settings)?,
            0o600,
        )
    }

    pub(crate) fn lock(&self) -> Result<File> {
        files::private_dir(&self.root.join("var"))?;
        let file = OpenOptions::new()
            .read(true)
            .write(true)
            .create(true)
            .truncate(false)
            .mode(0o600)
            .open(self.root.join("var/operation.lock"))?;
        file.try_lock()
            .context("Another stack operation is already running")?;
        Ok(file)
    }

    pub(crate) fn command(&self, name: &str) -> Result<Command> {
        let mut command = Command::new(name);
        command.current_dir(&self.root);
        if let Some(tools) = self
            .root
            .ancestors()
            .map(|p| p.join(".tools"))
            .find(|p| p.join("bin/cargo-deny").is_file())
        {
            let mut paths = vec![tools.join("bin")];
            if let Some(inherited) = env::var_os("PATH") {
                paths.extend(env::split_paths(&inherited));
            }
            command.env("PATH", env::join_paths(paths)?);
        }
        if name == "podman" {
            let version = process::text(Command::new("podman").arg("--version"))?;
            let major = version
                .split_whitespace()
                .nth(2)
                .and_then(|value| value.split('.').next())
                .context("Cannot determine the Podman version")?
                .parse::<u32>()?;
            if major < 6 {
                command.env(
                    "CONTAINERS_CONF_OVERRIDE",
                    self.root.join("infra/podman.conf"),
                );
            }
            command
                .arg("--root")
                .arg(self.root.join("var/podman/storage"))
                .arg("--runroot")
                .arg(self.root.join("var/podman/run"));
        }
        Ok(command)
    }

    pub(crate) fn platform(&self) -> Result<String> {
        let info: Value = serde_json::from_slice(
            &process::capture(self.command("podman")?.args(["info", "--format", "json"]))?.stdout,
        )?;
        Ok(format!(
            "{}/{}",
            field(&info, &["host", "os"])?
                .as_str()
                .context("Missing host OS")?,
            field(&info, &["host", "arch"])?
                .as_str()
                .context("Missing host architecture")?
        ))
    }

    pub(crate) fn configuration(&self, settings: &Settings) -> Result<Configuration> {
        let mut config: Configuration =
            toml::from_str(&fs::read_to_string(self.root.join("infra/services.toml"))?)?;
        ensure!(
            config.format == 1 && config.services.contains_key("caddy"),
            "Invalid services configuration"
        );
        if self.root.join("var/image-lock.json").is_file() && !settings.online {
            let lock: Value =
                serde_json::from_reader(File::open(self.root.join("var/image-lock.json"))?)?;
            for (name, service) in &mut config.services {
                field(&lock, &["services", name, "reference"])?
                    .as_str()
                    .context("Invalid image lock")?
                    .clone_into(&mut service.image);
            }
        }
        Ok(config)
    }

    pub(crate) fn initialize(&self, settings: &Settings) -> Result<()> {
        files::private_dir(&self.root.join("var/data"))?;
        let env_file = self.root.join(".env");
        if !env_file.exists() {
            let mut random = [0; 32];
            File::open("/dev/urandom")?.read_exact(&mut random)?;
            let secret = hex::encode(random);
            files::write(
                &env_file,
                format!("SEARXNG_SECRET={secret}\n").as_bytes(),
                0o600,
            )?;
        }
        fs::set_permissions(&env_file, Permissions::from_mode(0o600))?;
        for name in ["repos", "caddy/data", "caddy/config", "searxng"] {
            fs::create_dir_all(self.root.join("var/data").join(name))?;
        }
        fs::set_permissions(
            self.root.join("var/data/repos"),
            Permissions::from_mode(0o755),
        )?;
        let repository = self.root.join("var/data/repos/stack");
        if !repository.exists() {
            if self.root.join(".git").is_dir() {
                process::capture(
                    self.command("git")?
                        .args(["clone", "--bare", "."])
                        .arg(&repository),
                )?;
            } else {
                process::capture(
                    self.command("git")?
                        .args(["init", "--bare", "--initial-branch=main"])
                        .arg(&repository),
                )?;
            }
        }
        files::copy_tree(
            &self.root.join("infra/searxng"),
            &self.root.join("var/data/searxng"),
        )?;
        if settings.mode == Mode::Local {
            self.local_site(settings.port)?;
        }
        Ok(())
    }

    fn local_site(&self, port: u16) -> Result<()> {
        let generated = self.root.join("var/local/web");
        if generated.exists() {
            files::regular_tree(&generated)?;
            fs::remove_dir_all(&generated)?;
        }
        files::copy_tree(&self.root.join("web"), &generated)?;
        let index = generated.join("index.html");
        let html = fs::read_to_string(&index)?
            .replace("https://git.doan.luuduct.ai", "/git")
            .replace("https://search.doan.luuduct.ai", "/search")
            .replace("https://openpgpkey.luuduct.ai", "");
        files::write(&index, html.as_bytes(), 0o644)?;
        let template = self.root.join("infra/containers/cgit/cgitrc.local");
        let content = fs::read_to_string(&template)?
            .lines()
            .map(|line| {
                if line.starts_with("clone-prefix=") {
                    format!("clone-prefix=http://localhost:{port}/git")
                } else {
                    line.to_owned()
                }
            })
            .collect::<Vec<_>>()
            .join("\n");
        files::write(
            &self.root.join("var/local/cgitrc"),
            format!("{content}\n").as_bytes(),
            0o644,
        )
    }

    pub(crate) fn container_name(settings: &Settings, service: &str) -> String {
        format!("{}-{service}", settings.project)
    }

    pub(crate) fn inspect_containers(&self, settings: &Settings) -> Result<Vec<Value>> {
        let output = process::text(self.command("podman")?.args([
            "ps",
            "--all",
            "--quiet",
            "--filter",
            &format!("label=io.stack.project={}", settings.project),
        ]))?;
        let ids: Vec<_> = output.split_whitespace().collect();
        ensure!(!ids.is_empty(), "No stack containers found");
        Ok(serde_json::from_slice(
            &process::capture(self.command("podman")?.arg("inspect").args(ids))?.stdout,
        )?)
    }

    pub(crate) fn up(&self, settings: &Settings) -> Result<()> {
        ensure!(
            (1024..=65_534).contains(&settings.port),
            "Local port must be between 1024 and 65534"
        );
        self.initialize(settings)?;
        self.save(settings)?;
        let config = self.configuration(settings)?;
        let network = format!("{}-net", settings.project);
        if !process::available(
            self.command("podman")?
                .args(["network", "exists", &network]),
        ) {
            process::capture(
                self.command("podman")?
                    .args(["network", "create", &network]),
            )?;
        }
        let environment: BTreeMap<String, String> =
            dotenvy::from_path_iter(self.root.join(".env"))?
                .collect::<std::result::Result<_, _>>()?;
        for (name, service) in config
            .services
            .iter()
            .filter(|(_, service)| !service.gateway)
            .chain(
                config
                    .services
                    .iter()
                    .filter(|(_, service)| service.gateway),
            )
        {
            self.ensure_image(settings, service)?;
            self.start_service(settings, &network, name, service, &environment)?;
            self.wait_service(settings, name, service)?;
        }
        process::line(format_args!(
            "Running {}",
            if settings.mode == Mode::Production {
                "https://doan.luuduct.ai".to_owned()
            } else {
                format!("http://localhost:{}", settings.port)
            }
        ))
    }

    pub(crate) fn ensure_image(&self, settings: &Settings, service: &Service) -> Result<()> {
        if settings.mode == Mode::Local
            && (settings.online || !self.root.join("var/image-lock.json").exists())
            && let Some(context) = &service.build
        {
            return process::run(
                self.command("podman")?
                    .args(["build", "--tag", &service.image])
                    .arg(self.path(context)?),
            );
        }
        if process::available(
            self.command("podman")?
                .args(["image", "exists", &service.image]),
        ) {
            return Ok(());
        }
        ensure!(
            settings.mode == Mode::Local,
            "Production images must be built and deployed from the development machine"
        );
        process::run(self.command("podman")?.args(["pull", &service.image]))
    }

    fn start_service(
        &self,
        settings: &Settings,
        network: &str,
        name: &str,
        service: &Service,
        environment: &BTreeMap<String, String>,
    ) -> Result<()> {
        let container = Self::container_name(settings, name);
        let mut command = self.command("podman")?;
        command.args([
            "run",
            "--detach",
            "--replace",
            "--pull",
            "never",
            "--name",
            &container,
            "--network",
            network,
            "--network-alias",
            name,
            "--restart",
            "unless-stopped",
            "--label",
            &format!("io.stack.project={}", settings.project),
            "--label",
            &format!("io.stack.service={name}"),
            "--security-opt",
            "no-new-privileges",
        ]);
        if service.drop_capabilities {
            command.args(["--cap-drop", "ALL"]);
        }
        if service.gateway {
            let ports = if settings.mode == Mode::Local {
                let tls = settings.port.checked_add(1).context("Port overflow")?;
                [
                    format!("127.0.0.1:{}:80", settings.port),
                    format!("127.0.0.1:{tls}:443"),
                    format!("127.0.0.1:{tls}:443/udp"),
                ]
                .to_vec()
            } else {
                ["[::]:80:80", "[::]:443:443", "[::]:443:443/udp"]
                    .map(str::to_owned)
                    .to_vec()
            };
            for port in ports {
                command.args(["--publish", &port]);
            }
        }
        for key in &service.environment {
            command.arg("--env").arg(key).env(
                key,
                environment
                    .get(key)
                    .with_context(|| format!("Missing secret {key} in .env"))?,
            );
        }
        for mount in &service.mounts {
            let source = match mount.source.as_str() {
                "@caddy" => self.root.join(if settings.mode == Mode::Local {
                    "infra/Caddyfile.local"
                } else {
                    "infra/Caddyfile"
                }),
                "@web" => self.root.join(if settings.mode == Mode::Local {
                    "var/local/web"
                } else {
                    "web"
                }),
                "@cgit" => self.root.join(if settings.mode == Mode::Local {
                    "var/local/cgitrc"
                } else {
                    "infra/containers/cgit/cgitrc"
                }),
                other => self.path(other)?,
            };
            let mode = if mount.read_only { "ro,z" } else { "rw,z" };
            command
                .arg("--volume")
                .arg(format!("{}:{}:{mode}", source.display(), mount.target));
        }
        for mount in &service.tmpfs {
            command.args(["--tmpfs", mount]);
        }
        process::capture(command.arg(&service.image))?;
        Ok(())
    }

    fn wait_service(&self, settings: &Settings, name: &str, service: &Service) -> Result<()> {
        let container = Self::container_name(settings, name);
        for _attempt in 0..120 {
            if process::available(
                self.command("podman")?
                    .args(["exec", &container])
                    .args(&service.health),
            ) {
                return Ok(());
            }
            std::thread::sleep(Duration::from_millis(500));
        }
        bail!("Service did not become ready: {name}; inspect its Podman logs")
    }

    pub(crate) fn status(&self, settings: &Settings) -> Result<()> {
        process::run(self.command("podman")?.args([
            "ps",
            "--all",
            "--filter",
            &format!("label=io.stack.project={}", settings.project),
        ]))
    }

    pub(crate) fn down(&self, settings: &Settings) -> Result<()> {
        for name in self.configuration(settings)?.services.keys() {
            process::capture(self.command("podman")?.args([
                "rm",
                "--force",
                "--ignore",
                &Self::container_name(settings, name),
            ]))?;
        }
        let network = format!("{}-net", settings.project);
        if process::available(
            self.command("podman")?
                .args(["network", "exists", &network]),
        ) {
            process::capture(self.command("podman")?.args(["network", "rm", &network]))?;
        }
        Ok(())
    }

    fn path(&self, relative: &str) -> Result<PathBuf> {
        let path = Path::new(relative);
        ensure!(
            path.components()
                .all(|part| matches!(part, Component::Normal(_))),
            "Service paths must stay inside stack"
        );
        Ok(self.root.join(path))
    }
}

pub(crate) fn field<'a>(value: &'a Value, path: &[&str]) -> Result<&'a Value> {
    path.iter().try_fold(value, |node, key| {
        node.get(key)
            .with_context(|| format!("Missing JSON field {key}"))
    })
}