use serde::{
    de::{Error, Visitor},
    Deserialize, Deserializer, Serialize, Serializer,
};
use std::{
    collections::{BTreeMap, HashMap},
    fmt,
};

use crate::data::Styling;

/// How a status bar action button is decorated (OSC 5577).
#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, Deserialize, Serialize)]
pub enum StatusBarButtonStyle {
    /// `[Approve]` -- bracketed, no index.
    Boxed,
    /// `1:Approve` -- the button's 1-based position, then its label. Useful when
    /// something else binds those numbers to the same actions, so the bar shows
    /// which key does what.
    Indexed,
}

impl Default for StatusBarButtonStyle {
    fn default() -> Self {
        StatusBarButtonStyle::Boxed
    }
}

impl StatusBarButtonStyle {
    pub fn from_str(name: &str) -> Option<Self> {
        match name.trim().to_lowercase().as_str() {
            "boxed" => Some(StatusBarButtonStyle::Boxed),
            "indexed" => Some(StatusBarButtonStyle::Indexed),
            _ => None,
        }
    }
    pub fn possible_values() -> &'static str {
        "\"boxed\", \"indexed\""
    }
    /// How this style renders a button. `index` is 1-based.
    pub fn render(&self, index: usize, label: &str) -> String {
        match self {
            StatusBarButtonStyle::Boxed => format!("[{}]", label),
            StatusBarButtonStyle::Indexed => format!("{}:{}", index, label),
        }
    }
}

/// Visual treatment of the stacked-pane picker's entries.
#[derive(Debug, Clone, Copy, PartialEq, Eq, Deserialize, Serialize)]
pub enum StackListStyle {
    /// Each entry bracketed in vertical bars, with a "> " marker on the active
    /// one.
    Boxed,
    /// No brackets and no marker; the active entry is shown by inverting its
    /// foreground and background instead.
    Minimal,
}

impl Default for StackListStyle {
    fn default() -> Self {
        StackListStyle::Boxed
    }
}

impl StackListStyle {
    pub fn from_str(name: &str) -> Option<Self> {
        match name.trim().to_lowercase().as_str() {
            "boxed" => Some(StackListStyle::Boxed),
            "minimal" => Some(StackListStyle::Minimal),
            _ => None,
        }
    }
    pub fn possible_values() -> &'static str {
        "\"boxed\", \"minimal\""
    }
    /// Columns an entry spends on decoration. The picker's column arithmetic
    /// lives in Tab and must agree with the renderer, so both read this.
    pub fn decoration_cols(&self) -> usize {
        match self {
            // "> " marker, plus a border and a pad on each side
            StackListStyle::Boxed => 6,
            // one pad each side, so the inverted block has some air around it
            StackListStyle::Minimal => 2,
        }
    }
}

#[derive(Debug, Default, Clone, PartialEq, Deserialize, Serialize)]
pub struct UiConfig {
    pub pane_frames: FrameConfig,
}

impl UiConfig {
    pub fn merge(&self, other: UiConfig) -> Self {
        let mut merged = self.clone();
        merged.pane_frames = merged.pane_frames.merge(other.pane_frames);
        merged
    }
}

#[derive(Debug, Clone, PartialEq, Deserialize, Serialize)]
pub struct FrameConfig {
    pub rounded_corners: bool,
    pub hide_session_name: bool,
    pub title_alignment: crate::data::PaneTitleAlignment,
    /// outer gap between panes, expressed in ROWS (see Style::pane_gap_y).
    /// Columns are scaled by `gap_aspect` so the gap looks square.
    pub gap: usize,
    /// inner padding between a pane's frame and its content, per side.
    /// Already resolved at parse time (including any aspect correction).
    pub padding: crate::data::PanePadding,
    /// Columns per row. Terminal cells are roughly twice as tall as they are
    /// wide, so 1 row of gap needs ~2 columns to look like the same distance.
    /// 0 is treated as 1 (no correction).
    pub gap_aspect: usize,
    /// How strongly to desaturate the CONTENT of unfocused panes, 0-100.
    /// 0 disables it entirely (the default).
    pub inactive_grayscale: u8,
    /// Omit the auto-generated "Pane #N" placeholder title, so a pane shows no
    /// name until the user sets one or the running program sets a title.
    pub hide_default_pane_names: bool,
    /// Collapse to the swap layout named `responsive_layout` when the terminal
    /// is narrower than this many columns. 0 disables the whole feature.
    pub responsive_min_cols: usize,
    /// Name of the swap tiled layout to use when below the threshold.
    pub responsive_layout: String,
    /// Cap on how many entries the stacked-pane picker shows at once. The list
    /// windows around the focused entry and reports the rest as "+N". 0 = show
    /// every member, however many rows that takes.
    pub stack_list_max_rows: usize,
    /// Pack picker entries into a grid instead of one per row. The row cap then
    /// becomes a space budget rather than a count.
    pub stack_list_grid: bool,
    /// Visual treatment of picker entries.
    pub stack_list_style: StackListStyle,
    /// How status bar action buttons are decorated.
    pub status_bar_button_style: StatusBarButtonStyle,
}

/// Hand-written rather than derived: `gap_aspect` must default to 2 to match
/// the KDL parser's default. A derived Default would give 0, which makes a
/// parsed config disagree with a default-constructed one and shows up as
/// config round-trip diffs.
impl Default for FrameConfig {
    fn default() -> Self {
        FrameConfig {
            rounded_corners: false,
            hide_session_name: false,
            title_alignment: Default::default(),
            gap: 0,
            padding: Default::default(),
            gap_aspect: 2,
            inactive_grayscale: 0,
            hide_default_pane_names: false,
            responsive_min_cols: 0,
            responsive_layout: String::from("stacked"),
            stack_list_max_rows: 0,
            stack_list_grid: false,
            stack_list_style: StackListStyle::Boxed,
            status_bar_button_style: StatusBarButtonStyle::Boxed,
        }
    }
}

impl FrameConfig {
    fn aspect(&self) -> usize {
        self.gap_aspect.max(1)
    }
    /// (columns, rows) of outer gap
    pub fn resolved_gap(&self) -> (usize, usize) {
        (self.gap * self.aspect(), self.gap)
    }
    pub fn resolved_padding(&self) -> crate::data::PanePadding {
        self.padding
    }
}

impl FrameConfig {
    pub fn merge(&self, other: FrameConfig) -> Self {
        let mut merged = self.clone();
        merged.rounded_corners = other.rounded_corners;
        merged.hide_session_name = other.hide_session_name;
        merged.title_alignment = other.title_alignment;
        merged.gap = other.gap;
        merged.padding = other.padding;
        merged.gap_aspect = other.gap_aspect;
        merged.inactive_grayscale = other.inactive_grayscale;
        merged.hide_default_pane_names = other.hide_default_pane_names;
        merged.responsive_min_cols = other.responsive_min_cols;
        merged.responsive_layout = other.responsive_layout.clone();
        merged.stack_list_max_rows = other.stack_list_max_rows;
        merged.stack_list_grid = other.stack_list_grid;
        merged.stack_list_style = other.stack_list_style;
        merged.status_bar_button_style = other.status_bar_button_style;
        merged
    }
}

#[derive(Clone, PartialEq, Default, Serialize, Deserialize)]
pub struct Themes(HashMap<String, Theme>);

impl fmt::Debug for Themes {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        let mut stable_sorted = BTreeMap::new();
        for (theme_name, theme) in self.0.iter() {
            stable_sorted.insert(theme_name, theme);
        }
        write!(f, "{:#?}", stable_sorted)
    }
}

impl Themes {
    pub fn from_data(theme_data: HashMap<String, Theme>) -> Self {
        Themes(theme_data)
    }
    pub fn insert(&mut self, theme_name: String, theme: Theme) {
        self.0.insert(theme_name, theme);
    }
    pub fn merge(&self, mut other: Themes) -> Self {
        let mut merged = self.clone();
        for (name, theme) in other.0.drain() {
            merged.0.insert(name, theme);
        }
        merged
    }
    pub fn get_theme(&self, theme_name: &str) -> Option<&Theme> {
        self.0.get(theme_name)
    }
    pub fn inner(&self) -> &HashMap<String, Theme> {
        &self.0
    }
}

#[derive(Debug, Clone, PartialEq, Deserialize, Serialize)]
pub struct Theme {
    pub sourced_from_external_file: bool,
    #[serde(flatten)]
    pub palette: Styling,
}

#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
pub struct HexColor(u8, u8, u8);

impl From<HexColor> for (u8, u8, u8) {
    fn from(e: HexColor) -> (u8, u8, u8) {
        let HexColor(r, g, b) = e;
        (r, g, b)
    }
}

pub struct HexColorVisitor();

impl<'de> Visitor<'de> for HexColorVisitor {
    type Value = HexColor;

    fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
        write!(formatter, "a hex color in the format #RGB or #RRGGBB")
    }

    fn visit_str<E>(self, s: &str) -> Result<Self::Value, E>
    where
        E: Error,
    {
        if let Some(stripped) = s.strip_prefix('#') {
            return self.visit_str(stripped);
        }

        if s.len() == 3 {
            Ok(HexColor(
                u8::from_str_radix(&s[0..1], 16).map_err(E::custom)? * 0x11,
                u8::from_str_radix(&s[1..2], 16).map_err(E::custom)? * 0x11,
                u8::from_str_radix(&s[2..3], 16).map_err(E::custom)? * 0x11,
            ))
        } else if s.len() == 6 {
            Ok(HexColor(
                u8::from_str_radix(&s[0..2], 16).map_err(E::custom)?,
                u8::from_str_radix(&s[2..4], 16).map_err(E::custom)?,
                u8::from_str_radix(&s[4..6], 16).map_err(E::custom)?,
            ))
        } else {
            Err(Error::custom(
                "Hex color must be of form \"#RGB\" or \"#RRGGBB\"",
            ))
        }
    }
}

impl<'de> Deserialize<'de> for HexColor {
    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
    where
        D: Deserializer<'de>,
    {
        deserializer.deserialize_str(HexColorVisitor())
    }
}
impl Serialize for HexColor {
    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
    where
        S: Serializer,
    {
        serializer.serialize_str(format!("{:02X}{:02X}{:02X}", self.0, self.1, self.2).as_str())
    }
}

#[cfg(test)]
#[path = "./unit/theme_test.rs"]
mod theme_test;