using AcDream.Plugin.Abstractions;

namespace AcDream.Plugins.MossTank;

/// <summary>Settings that shape a buff pass. Defaults follow Virindi Tank's.</summary>
public sealed class BuffSettings
{
    /// <summary>
    /// VTank recasts buffs once they drop below five minutes remaining
    /// ("all buff spells are recast when they go below 5 minutes").
    /// </summary>
    public double RebuffWhenUnderSeconds { get; set; } = 300.0;

    /// <summary>
    /// How far the casting skill must exceed a spell's difficulty before the
    /// tier is considered reliable — VTank's
    /// <c>SpellDiffExcessThreshold-Buff</c>.
    /// </summary>
    public int SkillExcessOverDifficulty { get; set; } = 10;

    /// <summary>Buff every attribute (VTank's default).</summary>
    public bool BuffAttributes { get; set; } = true;

    /// <summary>
    /// The elemental/physical protections and Armor Self. VTank keeps these in
    /// their own profile (<c>BuffProfile_Prots</c>) and casts them by default.
    /// </summary>
    public bool BuffProtections { get; set; } = true;

    /// <summary>
    /// Self-cast weapon and caster auras — Blood Drinker, Heart Seeker, Swift
    /// Killer, Defender, Spirit Drinker.
    /// </summary>
    public bool BuffAuras { get; set; } = true;

    /// <summary>
    /// Banes — armour resistance, cast by targeting yourself. VTank keeps them
    /// in their own profile (<c>BuffProfile_Banes</c>) and casts them by default.
    /// </summary>
    public bool BuffBanes { get; set; } = true;

    /// <summary>
    /// The vital regeneration rates — Regeneration (health), Rejuvenation
    /// (stamina), Mana Renewal (mana). Cast last, as the tail of a pass.
    /// </summary>
    public bool BuffRegeneration { get; set; } = true;

    /// <summary>
    /// Anything else self-targeted with a duration. Off by default: useful to
    /// some characters, wasted mana for others, and it is the bucket anything
    /// unrecognised falls into.
    /// </summary>
    public bool BuffOther { get; set; }

    /// <summary>
    /// Buff trained and specialised skills only — VTank's stated default:
    /// "automatically buffs every Attribute and Skill you have trained".
    /// </summary>
    public bool BuffTrainedSkillsOnly { get; set; } = true;
}

/// <summary>
/// Chooses which buffs to cast, at which tier, in which order.
/// </summary>
/// <remarks>
/// A pure function of (buff lines, character state) so the policy can be tested
/// without a session. This is the part that stays in plugin-land: the host
/// supplies spell data and a cast primitive, MossTank decides.
/// </remarks>
public static class BuffPlan
{
    /// <param name="force">
    /// Virindi Tank's Force Buff: queue every wanted line at its best castable
    /// tier, ignoring what is already in force and how long it has left. The
    /// ordinary path skips buffs that are already covered; forcing does not.
    /// </param>
    public static List<PluginSpellInfo> Build(
        IReadOnlyList<BuffLine> lines,
        IReadOnlyList<PluginSkillInfo> skills,
        IReadOnlyList<PluginAttributeInfo> attributes,
        IReadOnlyList<PluginActiveEnchantment> active,
        BuffSettings settings,
        bool force = false)
    {
        var trainedSkills = new Dictionary<string, PluginSkillInfo>(
            StringComparer.OrdinalIgnoreCase);
        foreach (PluginSkillInfo skill in skills)
        {
            if (!settings.BuffTrainedSkillsOnly
                || skill.Training is PluginSkillTraining.Trained
                    or PluginSkillTraining.Specialized)
            {
                trainedSkills[skill.Name] = skill;
            }
        }

        var attributeNames = new HashSet<string>(StringComparer.OrdinalIgnoreCase);
        foreach (PluginAttributeInfo attribute in attributes)
            attributeNames.Add(attribute.Name);

        // Strongest in-force tier per family, and its remaining time.
        var inForce = new Dictionary<uint, (int Tier, double Seconds)>();
        foreach (PluginActiveEnchantment enchantment in active)
        {
            if (enchantment.Family == 0)
                continue;
            if (!inForce.TryGetValue(enchantment.Family, out var held)
                || enchantment.Tier > held.Tier)
            {
                inForce[enchantment.Family] =
                    (enchantment.Tier, enchantment.SecondsRemaining);
            }
        }

        var skillLevels = new Dictionary<uint, uint>();
        foreach (PluginSkillInfo skill in skills)
            skillLevels[skill.SkillId] = skill.Current;

        var plan = new List<(int Rank, PluginSpellInfo Spell)>();

        foreach (BuffLine line in lines)
        {
            bool wanted = line.Kind switch
            {
                BuffTargetKind.Attribute =>
                    settings.BuffAttributes && attributeNames.Contains(line.TargetName),
                BuffTargetKind.Skill => trainedSkills.ContainsKey(line.TargetName),
                BuffTargetKind.Protection => settings.BuffProtections,
                BuffTargetKind.Aura => settings.BuffAuras,
                BuffTargetKind.Bane => settings.BuffBanes,
                BuffTargetKind.Regeneration => settings.BuffRegeneration,
                BuffTargetKind.Other => settings.BuffOther,
                _ => false,
            };
            if (!wanted)
                continue;

            if (!TryPickTier(line, skillLevels, settings, out PluginSpellInfo pick))
                continue;

            if (!force
                && inForce.TryGetValue(line.Family, out var held)
                && held.Tier >= pick.Tier
                && held.Seconds >= settings.RebuffWhenUnderSeconds)
            {
                continue;   // already covered at this strength, and not expiring
            }

            plan.Add((CastRank(line, pick), pick));
        }

        // Retail's order first; cheapest-first only breaks ties, so that if mana
        // runs out mid-pass the casualties are the cheapest of the last group
        // rather than something the rest of the pass depended on.
        plan.Sort(static (a, b) =>
        {
            if (a.Rank != b.Rank)
                return a.Rank.CompareTo(b.Rank);
            if (a.Spell.ManaCost != b.Spell.ManaCost)
                return a.Spell.ManaCost.CompareTo(b.Spell.ManaCost);
            return a.Spell.SpellId.CompareTo(b.Spell.SpellId);
        });

        var ordered = new List<PluginSpellInfo>(plan.Count);
        foreach ((int _, PluginSpellInfo spell) in plan)
            ordered.Add(spell);
        return ordered;
    }

    /// <summary>Skill ids of the three schools that carry self-buffs.</summary>
    private const uint CreatureEnchantmentSkill = 31;
    private const uint ItemEnchantmentSkill = 32;
    private const uint LifeMagicSkill = 33;

    /// <summary>
    /// Where a buff falls in retail's casting order. Lower casts earlier.
    /// </summary>
    /// <remarks>
    /// <para>
    /// This is a <b>dependency order</b>, not a preference. Each group raises
    /// what the next group is cast with, so casting out of order means casting
    /// at a lower skill than the character could have had:
    /// </para>
    /// <list type="number">
    ///   <item><b>Creature Enchantment</b>, and within it, in this order:
    ///     <list type="bullet">
    ///       <item>the <b>Creature Enchantment</b> skill itself, which every
    ///         remaining creature buff is then cast with;</item>
    ///       <item><b>Focus</b>, then <b>Willpower</b>, then <b>Endurance</b> —
    ///         Focus and Self are the attributes the Item Enchantment and Life
    ///         Magic skills derive from, so raising them raises the skill that
    ///         groups 2 and 3 are cast with;</item>
    ///       <item>everything else creature.</item>
    ///     </list>
    ///   </item>
    ///   <item><b>Item Enchantment</b> — the banes and weapon auras.</item>
    ///   <item><b>Life Magic</b> last — the protections and Armor Self, then
    ///     the vital regeneration rates to finish.</item>
    /// </list>
    /// <para>
    /// <b>Willpower is matched as "Self".</b> Retail's spell is named Willpower
    /// but its description reads "Increases the caster's Self by 10 points", and
    /// classification comes from the description, so the attribute name here is
    /// the one retail actually writes.
    /// </para>
    /// </remarks>
    public static int CastRank(BuffLine line, PluginSpellInfo pick)
    {
        int school = pick.School switch
        {
            CreatureEnchantmentSkill => 0,
            ItemEnchantmentSkill => 1,
            LifeMagicSkill => 2,
            _ => 3,   // war/void and anything unschooled trail the rest
        };

        int within = school switch
        {
            0 => CreatureOrder(line),
            2 => LifeOrder(line),
            _ => 0,   // the item group has no internal order
        };
        return (school * 10) + within;
    }

    /// <summary>
    /// Inside Life Magic the protections go first and the vital regeneration
    /// rates finish the pass — they are the buffs that matter least if mana
    /// runs out, and the ones a character most often wants topped up last.
    /// </summary>
    private static int LifeOrder(BuffLine line) =>
        line.Kind == BuffTargetKind.Regeneration ? 1 : 0;

    private static int CreatureOrder(BuffLine line)
    {
        if (line.Kind == BuffTargetKind.Skill
            && Named(line.TargetName, "Creature Enchantment"))
        {
            return 0;
        }

        if (line.Kind == BuffTargetKind.Attribute)
        {
            if (Named(line.TargetName, "Focus"))
                return 1;
            if (Named(line.TargetName, "Self"))       // retail's Willpower line
                return 2;
            if (Named(line.TargetName, "Endurance"))
                return 3;
        }

        return 4;   // the rest of the creature spells
    }

    private static bool Named(string target, string name) =>
        string.Equals(target, name, StringComparison.OrdinalIgnoreCase);

    /// <summary>
    /// The strongest tier the character's skill in that school can carry.
    /// </summary>
    /// <remarks>
    /// Tiers are pre-sorted strongest-first, so the first one clearing the
    /// difficulty threshold is the answer. When no school skill is known the
    /// threshold cannot be evaluated, and the weakest tier is chosen rather
    /// than none — a buff that lands beats a buff that was never attempted.
    /// </remarks>
    public static bool TryPickTier(
        BuffLine line,
        IReadOnlyDictionary<uint, uint> skillLevels,
        BuffSettings settings,
        out PluginSpellInfo pick)
    {
        pick = default;
        if (line.Tiers.Count == 0)
            return false;

        foreach (PluginSpellInfo tier in line.Tiers)
        {
            if (tier.School == 0 || !skillLevels.TryGetValue(tier.School, out uint level))
                continue;
            if (level >= tier.Difficulty + settings.SkillExcessOverDifficulty)
            {
                pick = tier;
                return true;
            }
        }

        PluginSpellInfo weakest = line.Tiers[^1];
        if (weakest.School != 0 && skillLevels.ContainsKey(weakest.School))
            return false;   // school known, but even the weakest tier is out of reach

        pick = weakest;
        return true;
    }
}