//! The recommended PopupNotifications look: a banner across the top of the screen (docs/runicnpc/
//! PLAN.md stage 9e, D327).
//!
//! PopupNotifications is optional and the operator's to install (D141); its config is the
//! operator's too. The installer writes the banner into it only where it is **missing** or **still
//! exactly the plugin's own defaults** — every setting equal to 0.2.1's, the `Version` aside (D328).
//! A config with any one setting changed is somebody's choice and is kept whole, never merged into.
//! A config that does not parse is kept too: it is not ours to repair.
//!
//! The file carries a `Version`: PopupNotifications resets a config whose version is missing or
//! below 0.2.0 to its defaults on load, which would undo the banner at the first boot.

use std::path::Path;

use serde_json::Value;

/// The config's file name, in the framework's config directory beside the bridge's.
pub const FILE: &str = "PopupNotifications.json";

/// What is there now, and so what happens to it.
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum State {
    /// No config: the banner is written, and PopupNotifications reads it when it is installed.
    Missing,
    /// The plugin's own defaults, untouched: the banner replaces them. Holds the file's version.
    Defaults(Version),
    /// Changed by someone, or unreadable: kept.
    Theirs,
}

/// PopupNotifications' `VersionNumber`, as its config writes it.
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub struct Version {
    pub major: u64,
    pub minor: u64,
    pub patch: u64,
}

/// The version written into a config made from nothing: the release the defaults are read from.
const WRITTEN_VERSION: Version = Version {
    major: 0,
    minor: 2,
    patch: 1,
};

impl State {
    pub fn writes(self) -> bool {
        !matches!(self, Self::Theirs)
    }

    pub fn label(self) -> &'static str {
        match self {
            Self::Missing => "banner written (no config yet)",
            Self::Defaults(_) => "banner written (was the plugin's defaults)",
            Self::Theirs => "kept (not the plugin's defaults)",
        }
    }
}

/// Reads the config at `path` and says what it is.
pub fn inspect(path: &Path) -> State {
    match std::fs::read(path) {
        Err(e) if e.kind() == std::io::ErrorKind::NotFound => State::Missing,
        Err(_) => State::Theirs,
        Ok(bytes) => classify(&bytes),
    }
}

fn classify(bytes: &[u8]) -> State {
    let Ok(Value::Object(mut found)) = serde_json::from_slice::<Value>(bytes) else {
        return State::Theirs;
    };
    let version = found.remove("Version");
    let Ok(Value::Object(mut defaults)) = serde_json::from_str::<Value>(&render(DEFAULTS, None))
    else {
        unreachable!("the defaults are valid JSON")
    };
    defaults.remove("Version");
    if !same(&Value::Object(found), &Value::Object(defaults)) {
        return State::Theirs;
    }
    State::Defaults(
        version
            .as_ref()
            .and_then(read_version)
            .unwrap_or(WRITTEN_VERSION),
    )
}

fn read_version(v: &Value) -> Option<Version> {
    Some(Version {
        major: v.get("Major")?.as_u64()?,
        minor: v.get("Minor")?.as_u64()?,
        patch: v.get("Patch")?.as_u64()?,
    })
}

/// JSON equality with numbers compared as numbers: the plugin writes its floats through
/// Newtonsoft, and a value written `1.0` by one framework and `1` by another is the same setting.
fn same(a: &Value, b: &Value) -> bool {
    match (a, b) {
        (Value::Number(x), Value::Number(y)) => match (x.as_f64(), y.as_f64()) {
            (Some(x), Some(y)) => (x - y).abs() < 1e-6,
            _ => false,
        },
        (Value::Object(x), Value::Object(y)) => {
            x.len() == y.len() && x.iter().all(|(k, v)| y.get(k).is_some_and(|w| same(v, w)))
        }
        (Value::Array(x), Value::Array(y)) => {
            x.len() == y.len() && x.iter().zip(y).all(|(v, w)| same(v, w))
        }
        _ => a == b,
    }
}

/// The banner, as the file to write for `state`. `None` for a config that is kept.
pub fn banner_for(state: State) -> Option<String> {
    match state {
        State::Missing => Some(render(BANNER, Some(WRITTEN_VERSION))),
        State::Defaults(version) => Some(render(BANNER, Some(version))),
        State::Theirs => None,
    }
}

/// One look: the eleven settings PopupNotifications has.
struct Look {
    left: &'static str,
    bottom: &'static str,
    width: &'static str,
    height: &'static str,
    spacing: &'static str,
    close: bool,
    alpha: &'static str,
    font: &'static str,
    font_size: u32,
}

/// PopupNotifications 0.2.1's `GetBaseConfig()`: a small grey box at the right of the screen.
const DEFAULTS: Look = Look {
    left: "0.8",
    bottom: "0.78",
    width: "0.19",
    height: "0.1",
    spacing: "0.01",
    close: true,
    alpha: "0.5",
    font: "droidsansmono.ttf",
    font_size: 12,
};

/// The recommended look (9d player session, 2026-10-09): a banner across the top of the screen.
const BANNER: Look = Look {
    left: "0.15",
    bottom: "0.87",
    width: "0.7",
    height: "0.07",
    spacing: "0.005",
    close: false,
    alpha: "0.8",
    font: "robotocondensed-bold.ttf",
    font_size: 18,
};

/// The config file, laid out as the plugin writes it. Duration, the most shown, both colours and
/// the close button's transparency are the plugin's own in both looks.
fn render(look: Look, version: Option<Version>) -> String {
    let version = version.unwrap_or(WRITTEN_VERSION);
    format!(
        r##"{{
  "Notification duration (in seconds)": 8,
  "Maximum notifications shown at any time": 6,
  "UI Positioning": {{
    "Position of the left side of notification (0.0 - 1.0)": {left},
    "Position of the bottom of noticiation (0.0 - 1.0)": {bottom},
    "Width (0.0 - 1.0)": {width},
    "Height (0.0 - 1.0)": {height},
    "Space between notification (0.0 - 1.0)": {spacing}
  }},
  "UI Options": {{
    "Show close button": {close},
    "Panel color (hex)": "#2b2b2b",
    "Panel transparency (0.0 - 1.0)": {alpha},
    "Close button color (hex)": "#d85540",
    "Close button transparency (0.0 - 1.0)": 0.5,
    "Font": "{font}",
    "Font size": {font_size}
  }},
  "Version": {{
    "Major": {major},
    "Minor": {minor},
    "Patch": {patch}
  }}
}}"##,
        left = look.left,
        bottom = look.bottom,
        width = look.width,
        height = look.height,
        spacing = look.spacing,
        close = look.close,
        alpha = look.alpha,
        font = look.font,
        font_size = look.font_size,
        major = version.major,
        minor = version.minor,
        patch = version.patch,
    )
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::util::TempDir;

    /// The file PopupNotifications 0.2.1 wrote on both rigs at its first load (2026-10-09).
    const RIG_DEFAULTS: &str = r##"{
  "Notification duration (in seconds)": 8,
  "Maximum notifications shown at any time": 6,
  "UI Positioning": {
    "Position of the left side of notification (0.0 - 1.0)": 0.8,
    "Position of the bottom of noticiation (0.0 - 1.0)": 0.78,
    "Width (0.0 - 1.0)": 0.19,
    "Height (0.0 - 1.0)": 0.1,
    "Space between notification (0.0 - 1.0)": 0.01
  },
  "UI Options": {
    "Show close button": true,
    "Panel color (hex)": "#2b2b2b",
    "Panel transparency (0.0 - 1.0)": 0.5,
    "Close button color (hex)": "#d85540",
    "Close button transparency (0.0 - 1.0)": 0.5,
    "Font": "droidsansmono.ttf",
    "Font size": 12
  },
  "Version": {
    "Major": 0,
    "Minor": 2,
    "Patch": 1
  }
}"##;

    #[test]
    fn a_missing_config_gets_the_banner_with_a_version() {
        let dir = TempDir::new("rg-popup-missing").unwrap();
        let state = inspect(&dir.path().join(FILE));
        assert_eq!(state, State::Missing);
        let written: Value = serde_json::from_str(&banner_for(state).unwrap()).unwrap();
        assert_eq!(written["UI Positioning"]["Width (0.0 - 1.0)"], 0.7);
        assert_eq!(written["UI Options"]["Show close button"], false);
        assert_eq!(written["UI Options"]["Font"], "robotocondensed-bold.ttf");
        assert_eq!(written["UI Options"]["Font size"], 18);
        // Without a version the plugin resets the file to its defaults at load.
        assert_eq!(written["Version"]["Minor"], 2);
    }

    #[test]
    fn the_plugins_own_defaults_are_replaced_and_their_version_kept() {
        assert_eq!(
            classify(RIG_DEFAULTS.as_bytes()),
            State::Defaults(WRITTEN_VERSION)
        );
        let later = RIG_DEFAULTS.replace("\"Patch\": 1", "\"Patch\": 4");
        let state = classify(later.as_bytes());
        assert_eq!(
            state,
            State::Defaults(Version {
                major: 0,
                minor: 2,
                patch: 4
            })
        );
        assert!(banner_for(state).unwrap().contains("\"Patch\": 4"));
        // A whole number written as a float is still the default.
        let floats = RIG_DEFAULTS.replace("\"Font size\": 12", "\"Font size\": 12.0");
        assert!(matches!(classify(floats.as_bytes()), State::Defaults(_)));
    }

    #[test]
    fn the_rendered_defaults_are_the_file_the_plugin_writes() {
        let ours: Value = serde_json::from_str(&render(DEFAULTS, None)).unwrap();
        let rig: Value = serde_json::from_str(RIG_DEFAULTS).unwrap();
        assert_eq!(ours, rig);
    }

    #[test]
    fn any_change_keeps_the_whole_config() {
        for changed in [
            RIG_DEFAULTS.replace("\"Font size\": 12", "\"Font size\": 14"),
            RIG_DEFAULTS.replace(
                "\"Notification duration (in seconds)\": 8",
                "\"Notification duration (in seconds)\": 9",
            ),
            RIG_DEFAULTS.replace("#2b2b2b", "#000000"),
            render(BANNER, None),
            "{ not json".to_string(),
            "[]".to_string(),
        ] {
            let state = classify(changed.as_bytes());
            assert_eq!(state, State::Theirs, "{changed}");
            assert_eq!(banner_for(state), None);
        }
    }

    #[test]
    fn a_config_with_a_setting_added_or_missing_is_theirs() {
        let mut v: Value = serde_json::from_str(RIG_DEFAULTS).unwrap();
        v["Extra"] = Value::Bool(true);
        assert_eq!(classify(v.to_string().as_bytes()), State::Theirs);
        let mut v: Value = serde_json::from_str(RIG_DEFAULTS).unwrap();
        v.as_object_mut().unwrap().remove("UI Options");
        assert_eq!(classify(v.to_string().as_bytes()), State::Theirs);
    }
}