#include "game/ai/tasks.h"

#include <algorithm>

namespace sots::ai {
namespace {

struct Row {
    const char* name;
    int priority;
};

// Indexed by task type id. Both retired ids keep their priority and carry no name.
constexpr Row kTable[kTaskTypeCount] = {
    /* 0x00 */ {"AITSteamroll", 1250},
    /* 0x01 */ {"AITExplore", 600},
    /* 0x02 */ {"AITExploreInForce", 550},
    /* 0x03 */ {"AITEscortGate", 700},
    /* 0x04 */ {"AITEscortGateInvade", 400},
    /* 0x05 */ {"AITEscortGateInvadeGoal", 950},
    /* 0x06 */ {"AITDeployGateAt", 1400},
    /* 0x07 */ {"AITColonize", 900},
    /* 0x08 */ {"AITColonizeGoal", 970},
    /* 0x09 */ {"AITColonizeAt", 1300},
    /* 0x0a */ {"AITInvade", 500},
    /* 0x0b */ {"AITInvadeGate", 1000},
    /* 0x0c */ {"AITInvadeGoal", 930},
    /* 0x0d */ {"", 200},
    /* 0x0e */ {"AITDefendColonyIncoming", 1100},
    /* 0x0f */ {"", 300},
    /* 0x10 */ {"AITDefendGateIncoming", 1200},
    /* 0x11 */ {"AITKillEasterEgg", 800},
    /* 0x12 */ {"AITInterceptEnemy", 850},
    /* 0x13 */ {"AITMining", 350},
    /* 0x14 */ {"AITMiningReturn", 375},
    /* 0x15 */ {"AITAttackBlockade", 100},
    /* 0x16 */ {"AITAdvanceIdleShips", 0},
    /* 0x17 */ {"AITStockFreighters", 50},
    /* 0x18 */ {"AITRespondAttackSystem", 980},
    /* 0x19 */ {"AITRespondDefendSystem", 990},
    /* 0x1a */ {"AITNodeBore", 1275},
    /* 0x1b */ {"AITBuildStations", 910},
    /* 0x1c */ {"AITBuildPoliceShips", 75},
    /* 0x1d */ {"AITBuildDeepScanShips", 60},
    /* 0x1e */ {"AITRaid", 399},
    /* 0x1f */ {"AITRetrieveArtifact", 1},
    /* 0x20 */ {"AITReturnArtifact", 2},
};

// The two artifact tasks ignore their table entries entirely and return these instead. Keeping
// them here rather than in kTable is deliberate: the table values are real, reachable through
// nothing, and a future reader who "fixes" the table would be wrong.
constexpr int kRetrieveArtifactPriority = 1260;
constexpr int kReturnArtifactPriority = 1261;

constexpr bool InRange(TaskType t) {
    const int i = static_cast<int>(t);
    return i >= 0 && i < kTaskTypeCount;
}

// The shared tail every arm ends with, in call order.
void AppendCommonTail(std::vector<TaskType>& out, bool policeShips, bool deepScanShips) {
    out.push_back(TaskType::InterceptEnemy);
    out.push_back(TaskType::Mining);
    out.push_back(TaskType::MiningReturn);
    out.push_back(TaskType::AdvanceIdleShips);
    out.push_back(TaskType::Raid);
    out.push_back(TaskType::StockFreighters);
    out.push_back(TaskType::AttackBlockade);
    out.push_back(TaskType::BuildStations);
    if (policeShips) out.push_back(TaskType::BuildPoliceShips);
    if (deepScanShips) out.push_back(TaskType::BuildDeepScanShips);
}

// The goal group: one creator that builds four families.
void AppendGoalGroup(std::vector<TaskType>& out) {
    out.push_back(TaskType::ColonizeGoal);
    out.push_back(TaskType::EscortGateInvadeGoal);
    out.push_back(TaskType::Invade);
    out.push_back(TaskType::InvadeGoal);
}

// The two defensive families, behind the policy gate. DefendGateIncoming is Hiver-only.
void AppendDefensive(std::vector<TaskType>& out, bool policyNonZero, sim::Species species) {
    if (!policyNonZero) return;
    if (species == sim::Species::Hiver) out.push_back(TaskType::DefendGateIncoming);
    out.push_back(TaskType::DefendColonyIncoming);
}

}  // namespace

const char* TaskTypeName(TaskType t) { return InRange(t) ? kTable[static_cast<int>(t)].name : ""; }

int TablePriority(TaskType t) { return InRange(t) ? kTable[static_cast<int>(t)].priority : 0; }

int PriorityOf(const RankedTask& t, const TaskPriorityPolicy& policy) {
    switch (t.type) {
        case TaskType::RetrieveArtifact:
            return kRetrieveArtifactPriority;
        case TaskType::ReturnArtifact:
            return kReturnArtifactPriority;
        case TaskType::Invade:
            return t.priorityFlagBit0 ? policy.flaggedInvade : TablePriority(t.type);
        case TaskType::EscortGateInvade:
            return t.priorityFlagBit0 ? policy.flaggedEscortGateInvade : TablePriority(t.type);
        case TaskType::AttackBlockade:
            return t.overridePriority ? t.priority : TablePriority(t.type);
        default:
            return TablePriority(t.type);
    }
}

void Rank(std::vector<RankedTask>& tasks, const TaskPriorityPolicy& policy) {
    // std::stable_sort, not the introsort in game/config/msvc_sort.h: the original sorts a
    // std::list, and list::sort is a merge sort -- stable by construction, in every library.
    // The comparison is a strict greater-than on the priority, so equal keys never move.
    std::stable_sort(tasks.begin(), tasks.end(),
                     [&policy](const RankedTask& a, const RankedTask& b) {
                         return PriorityOf(a, policy) > PriorityOf(b, policy);
                     });
}

std::vector<TaskType> CreationOrder(sim::Species species, bool policyNonZero) {
    std::vector<TaskType> out;
    if (BuildsNoTasks(species)) return out;

    if (species == sim::Species::Hiver) {
        out.push_back(TaskType::Steamroll);
        out.push_back(TaskType::Colonize);
        out.push_back(TaskType::ColonizeAt);
        AppendDefensive(out, policyNonZero, species);
        out.push_back(TaskType::EscortGateInvade);
        out.push_back(TaskType::InvadeGate);
        out.push_back(TaskType::DeployGateAt);
        out.push_back(TaskType::EscortGate);
        AppendGoalGroup(out);
        AppendCommonTail(out, /*policeShips=*/true, /*deepScanShips=*/true);
        return out;
    }

    if (species == sim::Species::Zuul) {
        out.push_back(TaskType::Steamroll);
        out.push_back(TaskType::NodeBore);
        out.push_back(TaskType::Colonize);
        out.push_back(TaskType::ColonizeAt);
        AppendDefensive(out, policyNonZero, species);
        out.push_back(TaskType::KillEasterEgg);
        out.push_back(TaskType::Invade);
        out.push_back(TaskType::ExploreInForce);
        AppendGoalGroup(out);
        AppendCommonTail(out, /*policeShips=*/false, /*deepScanShips=*/true);
        return out;
    }

    // Human, Tarkas, Liir, Morrigi.
    out.push_back(TaskType::Steamroll);
    out.push_back(TaskType::Colonize);
    out.push_back(TaskType::ColonizeAt);
    AppendDefensive(out, policyNonZero, species);
    out.push_back(TaskType::KillEasterEgg);
    out.push_back(TaskType::Invade);
    out.push_back(TaskType::Explore);
    out.push_back(TaskType::ExploreInForce);
    AppendGoalGroup(out);
    AppendCommonTail(out, /*policeShips=*/true, /*deepScanShips=*/true);
    return out;
}

}  // namespace sots::ai