// Research: creatures studying in the library collect research points, and rooms, spells,
// towers, traps and doors are discovered one after another in a fixed order. Free play starts
// with the basics; a campaign mission knows what its story allows and may research what the
// next few missions would bring.

use crate::game::*;

// what is researched, in this order: (index in ui::TOOLS, research points)
pub const RESEARCH: &[(usize, f32)] = &[
    (5, 200.0),   // training hall
    (10, 250.0),  // heal
    (34, 250.0),  // haste
    (21, 300.0),  // forge
    (22, 250.0),  // spike pit
    (29, 250.0),  // wooden door
    (32, 300.0),  // seer's eye
    (15, 400.0),  // cannon tower
    (42, 300.0),  // guard post
    (12, 450.0),  // torture chamber
    (40, 450.0),  // prison
    (26, 300.0),  // alarm bell
    (35, 400.0),  // stoneskin
    (11, 500.0),  // summon
    (13, 550.0),  // temple
    (23, 500.0),  // poison vent
    (30, 500.0),  // iron door
    (33, 550.0),  // cave-in
    (18, 550.0),  // aerie
    (43, 550.0),  // arena
    (41, 600.0),  // graveyard
    (16, 650.0),  // magic tower
    (36, 600.0),  // gold rain
    (24, 650.0),  // fire jet
    (25, 650.0),  // stone roller
    (37, 700.0),  // invisibility
    (19, 700.0),  // steel walls
    (47, 700.0),  // drawbridge
    (28, 800.0),  // frost glow
    (48, 800.0),  // frost spell
    (38, 850.0),  // plague
    (27, 900.0),  // rune mine
    (39, 950.0),  // quake
    (44, 900.0),  // sacrifice altar
    (31, 1100.0), // magic door
];

// known from the start in free play
pub const BASE_TOOLS: &[usize] = &[0, 1, 2, 3, 4, 6, 7, 8, 9, 14, 17, 20, 45, 46, 49];

// campaign: what the next missions bring may be researched early
const LOOKAHEAD: usize = 4;

impl Game {
    // free play (None) or campaign mission i: what is known, what can be researched
    pub fn init_research(&mut self, mission: Option<usize>) {
        let n = crate::ui::TOOLS.len();
        match mission {
            None => {
                self.known = (0..n).map(|i| BASE_TOOLS.contains(&i)).collect();
                self.researchable = vec![true; n];
            }
            Some(m) => {
                let unlock = |i: usize| crate::campaign::TOOL_UNLOCK.get(i).copied().unwrap_or(0);
                self.known = (0..n).map(|i| unlock(i) <= m).collect();
                self.researchable = (0..n).map(|i| unlock(i) <= m + LOOKAHEAD && i != crate::game::RUNE_TOOL).collect();
            }
        }
        self.research = 0.0;
    }

    pub fn known(&self, tool: usize) -> bool {
        self.known.get(tool).copied().unwrap_or(true)
    }

    // the item being researched now: (index in RESEARCH)
    pub fn research_target(&self) -> Option<usize> {
        if self.known.is_empty() {
            return None;
        }
        RESEARCH.iter().position(|&(t, _)| !self.known(t) && self.researchable.get(t).copied().unwrap_or(false))
    }

    // the next items after the current one (for the library's info)
    pub fn research_queue(&self, n: usize) -> Vec<usize> {
        RESEARCH.iter().enumerate().filter(|(_, &(t, _))| !self.known(t) && self.researchable.get(t).copied().unwrap_or(false)).map(|(k, _)| k).take(n).collect()
    }

    // could this tool still be researched (for the locked-tool message)?
    pub fn can_research(&self, tool: usize) -> bool {
        !self.known(tool) && self.researchable.get(tool).copied().unwrap_or(false) && RESEARCH.iter().any(|&(t, _)| t == tool)
    }

    pub(crate) fn add_research(&mut self, points: f32) {
        if self.research_target().is_some() {
            self.research += points;
        }
    }

    pub(crate) fn update_research(&mut self) {
        let Some(k) = self.research_target() else { return };
        let (tool, cost) = RESEARCH[k];
        if self.research >= cost {
            self.research -= cost;
            if let Some(v) = self.known.get_mut(tool) {
                *v = true;
            }
            let name = crate::ui::tool_info(crate::ui::TOOLS[tool]).name;
            self.msg("msg.researched", vec![name]);
            self.sfx_ui(Sfx::LevelUp);
        }
    }
}

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

    #[test]
    fn studying_discovers_the_next_item() {
        let mut g = Game::new(9, 64, 64);
        assert!(!g.tool_allowed(5), "training hall must be researched");
        assert!(g.tool_allowed(2) && g.tool_allowed(6));
        let (cx, cy) = g.map.core;
        for y in cy - 8..=cy - 5 {
            for x in cx..=cx + 4 {
                let t = &mut g.map.t[idx(x, y)];
                t.kind = Kind::Library;
                t.owner = Owner::Player;
            }
        }
        g.recount();
        for k in 0..4 {
            g.spawn(EK::Mage, false, cx as f32 + 0.5 + k as f32, cy as f32 - 6.5, 3);
        }
        let mut found = false;
        for _ in 0..(20 * 400) {
            g.update(0.05);
            if g.tool_allowed(5) {
                found = true;
                break;
            }
        }
        assert!(found, "research points {}", g.research);
    }

    #[test]
    fn missions_know_their_tools_and_research_ahead() {
        let g = crate::campaign::start_mission(2, None);
        assert!(g.tool_allowed(5), "training hall known from mission 3");
        assert!(!g.tool_allowed(12));
        assert!(g.can_research(10), "heal comes soon and can be researched");
        assert!(!g.can_research(31), "magic doors are far away");
    }
}