---------------------------------------------------------------------------
-- runrest.lua:
-- Controls shift-running and resting stop conditions.
--
-- To use this, add this line to your init.txt:
--   lua_file = lua/runrest.lua
--
-- What it does:
--
--  * Any message in runrest_ignore_message will *not* stop your run.
--  * Poison damage of x will be ignored if you have at least y hp if you've
--    defined a runrest_ignore_poison = x:y option.
--  * Any monster in runrest_ignore_monster will *not* stop your run
--    if it's at least the specified distance away.
--    You can specify this with runrest_ignore_monster = regex:distance.
--
-- IMPORTANT: You must define runrest_ options *after* sourcing runrest.lua.
---------------------------------------------------------------------------

g_rr_ignored = { }

chk_interrupt_activity.run = function (iname, cause, extra)
    if not rr_check_params() then
        return false
    end

    if iname == 'message' then
        return rr_handle_message(cause, extra)
    end

    if iname == 'hp_loss' then
        return rr_handle_hploss(cause, extra)
    end

    return false
end

chk_interrupt_activity.butcher = function (iname, cause, extra)
    if not rr_check_params() then
        return false
    end

    if iname == 'hp_loss' then
        return rr_handle_hploss(cause, extra)
    end

    return false
end

-- run no longer automatically implies rest as of 0.1.3.
chk_interrupt_activity.rest = chk_interrupt_activity.run
chk_interrupt_activity.travel = chk_interrupt_activity.run

function rr_handle_message(cause, extra)
    local ch, mess = rr_split_channel(cause)
    for _, x in ipairs(g_rr_ignored) do
        if x.filter:matches(mess, ch) then
            return x.value
        end
    end
    return false
end

function rr_split_channel(s)
    local chi = string.find(s, ':')
    local channel = -1
    if chi and chi > 1 then
        local chstr = string.sub(s, 1, chi - 1)
        channel = crawl.msgch_num(chstr)
    end

    local sor = s
    if chi then
        s = string.sub(s, chi + 1, -1)
    end

    return channel, s
end

function rr_handle_hploss(hplost, source)
    -- source == 1 for poisoning
    if not g_rr_yhpmin or not g_rr_hplmax or source ~= 1 then
        return false
    end

    -- If the hp lost is smaller than configured, and you have more than the
    -- minimum health, ignore this poison event.
    if hplost <= g_rr_hplmax and you.hp() >= g_rr_yhpmin then
        return nil
    end

    return false
end

function rr_check_params()
    if ( not g_rr_hplmax or not g_rr_yhpmin )
            and options.runrest_ignore_poison
    then
        local opt = options.runrest_ignore_poison
        local hpl, hpm
        _, _, hpl, hpm = string.find(opt, "(%d+)%s*:%s*(%d+)")
        if hpl and hpm then
            g_rr_hplmax = tonumber(hpl)
            g_rr_yhpmin = tonumber(hpm)
        end
    end
    return true
end

function rr_add_message(s, v)
    local typ = v == nil and "nil" or v and "true" or "false"
    local channel, str = rr_split_channel(s)
    table.insert(g_rr_ignored,
                 { filter = crawl.message_filter(str, channel),
                   value = v })
end

function rr_message_adder(v)
    local function rr_add_messages(key, value)
        local segs = crawl.split(value, ',')
        for _, s in ipairs(segs) do
            rr_add_message(s, v)
        end
    end
    return rr_add_messages
end

chk_lua_option.runrest_ignore_message = rr_message_adder(nil)
chk_lua_option.runrest_stop_message = rr_message_adder(true)
-- alias for compatibility with obsolete travel_stop_message
chk_lua_option.travel_stop_message = rr_message_adder(true)
-----------------------------------------------------------------------

g_rr_monsters        = { {}, {} }
g_rr_monsters_moving = { {}, {} }

function rr_add_monster(mons_table, s)
    local parts = crawl.split(s, ":")

    if #parts ~= 2 then
        return
    end

    local regexp = parts[1]
    local dist   = tonumber(parts[2])

    if dist == 0 then
        return
    end

    table.insert( mons_table[1], crawl.regex( regexp ) )
    table.insert( mons_table[2], dist )
end

function rr_add_monsters(key, value)
    local mons_table

    if (key == "runrest_ignore_monster") then
        mons_table = g_rr_monsters
    elseif (key == "runrest_ignore_monster_moving") then
        mons_table = g_rr_monsters_moving
    else
        return
    end

    local segs = crawl.split(value, ',')
    for _, s in ipairs(segs) do
        rr_add_monster(mons_table, s)
    end
end

function ch_mon_is_safe(mon, default_is_safe, moving, dist)
    if default_is_safe then
        return true
    end

    local mons_table

    -- If player is moving and the monster is in g_rr_monsters_moving,
    -- then we do the distance comparison without decreasing the
    -- distance value.
    if moving then
        mons_table  = g_rr_monsters_moving

        for i = 1, #mons_table[1] do
            local m        = mons_table[1][i]
            local min_dist = mons_table[2][i]

            if m:matches(mon:desc()) then
                return min_dist <= dist
            end
        end
    end

    mons_table = g_rr_monsters

    -- Reduce distance by 1 if moving, since the safety check is
    -- done *before* moving closer to the monster
    if moving then
        dist = dist - 1
    end

    for i = 1, #mons_table[1] do
        local m        = mons_table[1][i]
        local min_dist = mons_table[2][i]

        if m:matches(mon:desc()) then
            return min_dist <= dist
        end
    end

    return false
end

chk_lua_option.runrest_ignore_monster            = rr_add_monsters
chk_lua_option.runrest_ignore_monster_moving     = rr_add_monsters
