//! TRACES: FR-DEV-6
//! The presets that ship with the application.
//!
//! # Shipped, not seeded
//!
//! The first six used to be *copied* into the photographer's own library on
//! the first run and were theirs from then on. That was the right answer for
//! six, and it cannot grow: a copy is frozen at the version that made it, so a
//! better "Portra" in the next release would reach nobody who already had the
//! old one, and re-seeding would overwrite a preset someone had tuned. So the
//! shipped set is now read from the binary every time, never written to the
//! user's file, and changes when the application does.
//!
//! # Your copy wins, as long as it keeps the name
//!
//! Saving over a shipped preset's name makes the photographer's version the
//! one that name means, here and in every apply. It is still *that* preset —
//! listed where the shipped one was, marked as changed — and deleting it
//! reveals the shipped one again, which is what "revert" means to the person
//! pressing it. Renaming it cuts the link: it becomes one of their own, and
//! the shipped preset reappears beside it. The lookup is by name because the
//! name is what the photographer sees and chooses by; an id they never see
//! would link two presets they believe are different.
//!
//! # Looks, not whole edits
//!
//! Every shipped preset reaches only the operations it names
//! ([`Reach::Named`]): a look applied to a corrected photograph must keep the
//! correction. A photographer's own saved edits keep [`Reach::Whole`], which
//! is what saving an edit has always meant.
//!
//! # Why the data is text files
//!
//! The same format the user's library is written in, so a shipped preset can
//! be read, diffed and copied into one's own library by hand, and each file
//! can say in a comment where its looks came from — the attribution a licence
//! may require travels with the data it covers.
//!
//! # Why this lives in the core
//!
//! It names operations — "Punch" is a statement about contrast and clarity —
//! and nothing in `ui/` may (`ui_names_no_operation.rs`, ARCH §4.3a). The
//! frontend asks for the listing and applies what it is handed.

use crate::preset::{Preset, PresetLibrary, Reach};

/// One group of shipped presets, as the sheet lists it.
pub struct Section {
    /// A stable identifier, for a frontend that remembers which sections a
    /// photographer folded away. Never shown.
    pub id: &'static str,
    /// What the section is called on screen, as a category path: `/`
    /// separates the levels, so `Film/Colour` is a folder inside `Film`. The
    /// same spelling a photographer's own preset names use for theirs.
    pub title: &'static str,
    /// The presets in it, every one reaching only what it names.
    pub presets: PresetLibrary,
}

/// The files, in the order the sheet lists them.
const SECTIONS: &[(&str, &str, &str)] = &[
    (
        "essentials",
        "Essentials",
        include_str!("../presets/essentials.drpl"),
    ),
    ("skies", "Skies", include_str!("../presets/skies.drpl")),
    ("vivid", "Vivid", include_str!("../presets/vivid.drpl")),
    (
        "colour_film",
        "Film/Colour",
        include_str!("../presets/colour_film.drpl"),
    ),
    (
        "cinema_film",
        "Film/Cinema",
        include_str!("../presets/cinema_film.drpl"),
    ),
    (
        "bw_film",
        "Film/Black and white",
        include_str!("../presets/bw_film.drpl"),
    ),
];

/// Every shipped section, parsed.
///
/// Parsed on each call rather than held: it is a few kilobytes read when the
/// preset sheet is drawn, and a static would be one more thing to keep
/// consistent with the files in a test. A file that fails to parse costs its
/// section, with a warning, rather than the sheet — and the tests below make
/// sure none does.
pub fn sections() -> Vec<Section> {
    SECTIONS
        .iter()
        .filter_map(|(id, title, text)| match PresetLibrary::parse(text) {
            Ok(library) => Some(Section {
                id,
                title,
                presets: as_looks(library),
            }),
            Err(e) => {
                log::warn!("shipped preset section {id} is unreadable ({e}); skipping");
                None
            }
        })
        .collect()
}

/// Mark every preset in `library` as a look.
///
/// Here rather than as a `reach = named` line in every block of every file:
/// the rule is about where a preset came from, and a file that forgot the
/// line would ship a preset that wiped a photographer's corrections.
fn as_looks(library: PresetLibrary) -> PresetLibrary {
    let mut looks = PresetLibrary::default();
    for (name, preset) in library.iter() {
        let _ = looks.insert(name, preset.clone().with_reach(Reach::Named));
    }
    looks
}

/// Where a listed preset comes from.
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum Origin {
    /// The photographer's own, with no shipped preset of that name.
    Yours,
    /// Shipped, and not overridden.
    Shipped,
    /// Shipped, and overridden by the photographer's copy under the same
    /// name. The copy is what applies; deleting it reverts to the shipped one.
    Changed,
}

/// One row of the preset sheet.
#[derive(Debug, Clone, PartialEq, Eq)]
pub struct Listed {
    pub name: String,
    pub origin: Origin,
}

/// One group of rows: the photographer's own, then each shipped section.
#[derive(Debug, Clone, PartialEq, Eq)]
pub struct ListedSection {
    /// `None` for the photographer's own presets.
    pub id: Option<&'static str>,
    pub title: &'static str,
    pub rows: Vec<Listed>,
}

/// Everything the sheet lists, in order, with the photographer's copies
/// standing in for the shipped presets they override.
///
/// Their own presets come first, because a photographer reaches for their own
/// work more than for anybody's defaults, and a copy of a shipped preset is
/// listed in the shipped section rather than among their own — it is still
/// that preset, changed, and belongs where they would look for it.
pub fn listing(yours: &PresetLibrary) -> Vec<ListedSection> {
    let shipped = sections();
    let is_shipped = |name: &str| shipped.iter().any(|section| section.presets.contains(name));

    let mut out = vec![ListedSection {
        id: None,
        title: "Yours",
        rows: yours
            .names()
            .filter(|name| !is_shipped(name))
            .map(|name| Listed {
                name: name.to_string(),
                origin: Origin::Yours,
            })
            .collect(),
    }];
    out.extend(shipped.iter().map(|section| {
        ListedSection {
            id: Some(section.id),
            title: section.title,
            rows: section
                .presets
                .names()
                .map(|name| Listed {
                    name: name.to_string(),
                    origin: if yours.contains(name) {
                        Origin::Changed
                    } else {
                        Origin::Shipped
                    },
                })
                .collect(),
        }
    }));
    out
}

/// The preset a name means: the photographer's if they have one, the shipped
/// one otherwise.
pub fn lookup(yours: &PresetLibrary, name: &str) -> Option<Preset> {
    yours.get(name).cloned().or_else(|| {
        sections()
            .into_iter()
            .find_map(|section| section.presets.get(name).cloned())
    })
}

/// Whether `name` is a shipped preset's.
pub fn is_shipped(name: &str) -> bool {
    sections()
        .iter()
        .any(|section| section.presets.contains(name))
}

/// Remove the copies a first run used to seed, where they are still exactly
/// as seeded. Returns how many went.
///
/// Those copies would otherwise all list as changed — overriding a shipped
/// preset with an identical one — and would freeze the six at their old
/// values forever. One that differs in any way was tuned by somebody and is
/// kept: it is theirs, and it now overrides the shipped one, which is the
/// rule above doing what it is for.
///
/// Compared on the parameters and the film and not on [`Reach`]: the seeded
/// copies were whole edits, the shipped ones are looks, and that difference
/// is the thing this migration exists to deliver.
pub fn forget_unchanged_copies(yours: &mut PresetLibrary) -> usize {
    let shipped = sections();
    let stale: Vec<String> = yours
        .iter()
        .filter(|(name, preset)| {
            shipped.iter().any(|section| {
                section
                    .presets
                    .get(name)
                    .is_some_and(|s| s.params() == preset.params() && s.film() == preset.film())
            })
        })
        .map(|(name, _)| name.to_string())
        .collect();
    for name in &stale {
        yours.remove(name);
    }
    stale.len()
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::{EditGraph, Scope};

    fn all() -> Vec<(&'static str, String, Preset)> {
        sections()
            .into_iter()
            .flat_map(|s| {
                let id = s.id;
                s.presets
                    .iter()
                    .map(|(n, p)| (id, n.to_string(), p.clone()))
                    .collect::<Vec<_>>()
            })
            .collect()
    }

    #[test]
    fn every_file_parses_and_every_line_is_understood() {
        // A misspelt key would otherwise be kept as a line this build does
        // not understand — preserved faithfully, and doing nothing.
        assert_eq!(
            sections().len(),
            SECTIONS.len(),
            "a section failed to parse"
        );
        for (id, _, text) in SECTIONS {
            let library = PresetLibrary::parse(text).unwrap();
            assert_eq!(library.unread_lines(), 0, "{id} has lines nobody reads");
            assert!(!library.is_empty(), "{id} is empty");
        }
    }

    #[test]
    fn every_shipped_name_is_unique_across_sections() {
        // A name is what the lookup and the override key on. Two shipped
        // presets sharing one would make one of them unreachable.
        let mut names: Vec<String> = all().into_iter().map(|(_, n, _)| n).collect();
        let before = names.len();
        names.sort();
        names.dedup();
        assert_eq!(names.len(), before);
    }

    #[test]
    fn every_shipped_preset_is_a_look() {
        for (id, name, preset) in all() {
            assert_eq!(preset.reach(), Reach::Named, "{id}/{name}");
        }
    }

    #[test]
    fn every_shipped_preset_names_parameters_this_build_actually_has() {
        // A renamed parameter must break the build rather than ship a preset
        // that quietly does nothing.
        let graph = EditGraph::default_chain();
        let capabilities = graph.capabilities();
        for (id, name, preset) in all() {
            for (op, param) in preset.params().keys() {
                let capability = capabilities
                    .iter()
                    .find(|c| c.id.0 == op)
                    .unwrap_or_else(|| panic!("{id}/{name}: no operation {op:?}"));
                assert!(
                    capability.params.iter().any(|p| p.id.0 == param),
                    "{id}/{name}: operation {op:?} has no parameter {param:?}"
                );
            }
        }
    }

    #[test]
    fn every_shipped_preset_changes_something() {
        // A preset that applies to nothing teaches the photographer that the
        // list does not work.
        for (id, name, preset) in all() {
            let mut graph = EditGraph::default_chain();
            let rebake = preset.apply(&mut graph, Scope::adjustments());
            assert!(
                rebake.wanted().is_some() || Preset::capture(&graph) != Preset::default(),
                "{id}/{name} left the graph at its defaults"
            );
        }
    }

    #[test]
    fn no_shipped_preset_carries_a_crop() {
        for (id, name, preset) in all() {
            assert!(!preset.touches_framing(), "{id}/{name} carries framing");
        }
    }

    #[test]
    fn the_values_stay_inside_what_the_controls_accept() {
        // Clamping happens on apply, so an out-of-range literal would be
        // silently trimmed and the preset would not be the one written.
        for (id, name, preset) in all() {
            let mut graph = EditGraph::default_chain();
            preset
                .clone()
                .with_film(None)
                .apply(&mut graph, Scope::everything())
                .expect_no_film();
            for ((op, param), value) in preset.params() {
                let (op_id, param_id) = crate::preset::resolve(&graph, op, param).unwrap();
                assert_eq!(
                    graph.param(op_id, param_id),
                    Some(*value),
                    "{id}/{name}: {op}.{param} = {value} was clamped"
                );
            }
        }
    }

    // --- the listing and the override ------------------------------------

    fn yours_with(names: &[(&str, Preset)]) -> PresetLibrary {
        let mut lib = PresetLibrary::default();
        for (n, p) in names {
            lib.insert(n, p.clone()).unwrap();
        }
        lib
    }

    fn first_shipped() -> (String, Preset) {
        let (_, name, preset) = all().into_iter().next().unwrap();
        (name, preset)
    }

    #[test]
    fn your_copy_under_a_shipped_name_is_what_that_name_applies() {
        let (name, shipped) = first_shipped();
        let mine = Preset::default();
        let yours = yours_with(&[(&name, mine.clone())]);

        assert_eq!(lookup(&yours, &name), Some(mine));
        assert_eq!(lookup(&PresetLibrary::default(), &name), Some(shipped));
    }

    #[test]
    fn your_copy_is_listed_in_the_shipped_section_as_changed() {
        let (name, _) = first_shipped();
        let yours = yours_with(&[(&name, Preset::default()), ("Mine", Preset::default())]);
        let listing = listing(&yours);

        assert_eq!(listing[0].id, None);
        assert_eq!(
            listing[0].rows,
            vec![Listed {
                name: "Mine".into(),
                origin: Origin::Yours
            }],
            "an override must not be listed twice"
        );
        let row = listing[1..]
            .iter()
            .flat_map(|s| &s.rows)
            .find(|r| r.name == name)
            .unwrap();
        assert_eq!(row.origin, Origin::Changed);
    }

    #[test]
    fn deleting_your_copy_reverts_to_the_shipped_one() {
        let (name, shipped) = first_shipped();
        let mut yours = yours_with(&[(&name, Preset::default())]);
        yours.remove(&name);
        assert_eq!(lookup(&yours, &name), Some(shipped));
    }

    #[test]
    fn renaming_your_copy_cuts_the_link() {
        let (name, shipped) = first_shipped();
        let mut yours = yours_with(&[(&name, Preset::default())]);
        yours.rename(&name, "My version").unwrap();

        assert_eq!(lookup(&yours, &name), Some(shipped));
        assert_eq!(lookup(&yours, "My version"), Some(Preset::default()));
        assert_eq!(listing(&yours)[0].rows[0].name, "My version");
    }

    #[test]
    fn the_old_seeded_copies_are_forgotten_and_tuned_ones_kept() {
        // The six as a first run wrote them: the same parameters, as whole
        // edits, because that is what a seeded copy was.
        let essentials = sections().into_iter().next().unwrap().presets;
        let mut yours = PresetLibrary::default();
        for (name, preset) in essentials.iter() {
            yours
                .insert(name, preset.clone().with_reach(Reach::Whole))
                .unwrap();
        }
        let tuned = essentials.names().next().unwrap().to_string();
        yours.insert(&tuned, Preset::default()).unwrap();
        yours.insert("Mine", Preset::default()).unwrap();

        let forgotten = forget_unchanged_copies(&mut yours);

        assert_eq!(forgotten, essentials.len() - 1);
        assert!(yours.contains(&tuned), "a tuned copy was thrown away");
        assert!(yours.contains("Mine"));
        assert_eq!(yours.len(), 2);
    }
}