//! The role set every surface paints from.
//!
//! Roles are named for what they do, not for a container ladder. `surface_active`
//! is the selected panel and the hover fill; it is not "surface container
//! highest", because nothing in Lumbridge has to reason about how many
//! containers deep it is.
//!
//! Two rules the rest of the application depends on:
//!
//! - **Provenance roles are distinct from state roles.** Decision 0012 says a
//!   usage value is coloured by where it came from, never by how alarming it is.
//!   They are separate fields here so a theme cannot quietly collapse the two,
//!   and a test asserts the five stay pairwise distinguishable.
//! - **Nothing is derived lazily.** A `Palette` is computed once when the theme
//!   changes and then only read, so a render pass never runs the bisection.

use crate::color::Srgb;

/// Every colour the interface is allowed to use.
#[derive(Clone, Copy, Debug, Eq, PartialEq)]
pub struct Palette {
    /// The application frame: window background, sidebar, footer, tab gutter.
    pub chrome: Srgb,
    /// The work surface: panel bodies, terminals, editors.
    pub surface: Srgb,
    /// One step off the surface: unselected tabs, inline cards.
    pub surface_raised: Srgb,
    /// Two steps: the selected panel, hover fills, chip backgrounds.
    pub surface_active: Srgb,
    /// Floating above everything: the command palette, popovers, menus.
    pub surface_overlay: Srgb,
    /// The seam where the frame meets the content.
    pub surface_between: Srgb,
    pub border: Srgb,
    /// A divider that should be felt rather than seen.
    pub border_quiet: Srgb,
    pub text: Srgb,
    /// Secondary text. The theme's own comment colour, so it is legible against
    /// the surface by construction rather than by our guess.
    pub muted: Srgb,
    /// Focus rings, selection, the active tab underline.
    pub accent: Srgb,
    /// Black or white, whichever reads on `accent`.
    pub on_accent: Srgb,
    pub success: Srgb,
    pub danger: Srgb,
    /// A danger fill quiet enough to sit behind text.
    pub danger_container: Srgb,
    /// Needs a human. Paired with a glyph, never used alone.
    pub attention: Srgb,
    pub attention_wash: Srgb,
    /// Tooltips and inverted chips.
    pub inverse_surface: Srgb,
    pub on_inverse: Srgb,
    pub scrim: Srgb,
    pub is_dark: bool,
}

impl Palette {
    /// The colour a usage reading is drawn in, by where the number came from.
    ///
    /// Decision 0012's rule made explicit: the argument is a provenance, and
    /// there is no way to pass a value in, so this cannot accidentally become
    /// "red when low".
    #[must_use]
    pub const fn provenance(&self, provenance: Provenance) -> Srgb {
        match provenance {
            Provenance::Provider => self.success,
            Provenance::Harness => self.accent,
            Provenance::Local => self.text,
            Provenance::Estimated => self.attention,
            Provenance::Unavailable => self.muted,
        }
    }

    /// The five provenance colours, for the distinctness test.
    #[must_use]
    pub const fn provenance_roles(&self) -> [Srgb; 5] {
        [
            self.success,
            self.accent,
            self.text,
            self.attention,
            self.muted,
        ]
    }
}

/// Where a usage number came from.
///
/// A structural mirror of `lumbridge_core::UsageProvenance`, kept here so this
/// crate stays free of a dependency on the ledger. The UI maps between them.
#[derive(Clone, Copy, Debug, Eq, PartialEq)]
pub enum Provenance {
    Provider,
    Harness,
    Local,
    Estimated,
    Unavailable,
}