-- AD Crop Plan (ren logik)
-- Mangel pr. afgrøde over 12 måneder (lager + forventet høst mod kædens behov) og valg af marker der skal skifte
-- målafgrøde: "fri til kæden" -> auto, ellers forslag. Brugerens egen målafgrøde ændres aldrig automatisk.

ADCropPlan = {}
ADCropPlan.HORIZON_MONTHS = 12
ADCropPlan.MIN_SHARE = 0.10
ADCropPlan.MIN_HA = 0.5

function ADCropPlan.plannedFruit(field)
    if field.targetFruit ~= nil and field.targetFruit ~= "" then return field.targetFruit end
    return field.fruit
end

function ADCropPlan.shortages(demand, stock, fields, yields)
    local list = {}
    for fruit, perMonth in pairs(demand or {}) do
        local perHa = (yields or {})[fruit] or 0
        if perHa > 0 and (perMonth or 0) > 0 then
            local need = perMonth * ADCropPlan.HORIZON_MONTHS
            local supply = (stock or {})[fruit] or 0
            for _, field in ipairs(fields or {}) do
                if ADCropPlan.plannedFruit(field) == fruit then supply = supply + (field.areaHa or 0) * perHa end
            end
            local missing = need - supply
            local missingHa = missing / perHa
            if missing > need * ADCropPlan.MIN_SHARE and missingHa > ADCropPlan.MIN_HA then
                table.insert(list, {fruit = fruit, needLiters = need, supplyLiters = supply, missingLiters = missing, missingHa = missingHa})
            end
        end
    end
    table.sort(list, function(a, b)
        if a.missingHa ~= b.missingHa then return a.missingHa > b.missingHa end
        return a.fruit < b.fruit
    end)
    return list
end

local function isCandidate(field, used, dismissedFruit, fruit)
    if field.permanent or field.excluded then return false end
    local planned = ADCropPlan.plannedFruit(field)
    if planned ~= nil and planned ~= "" and used[planned] then return false end
    return dismissedFruit ~= fruit
end

function ADCropPlan.choose(shortages, fields, usedFruits, yields, prices, dismissed)
    local actions, taken = {}, {}
    local used = usedFruits or {}
    for _, shortage in ipairs(shortages or {}) do
        local remaining = shortage.missingHa
        local candidates = {}
        for _, field in ipairs(fields or {}) do
            if not taken[field.id] and isCandidate(field, used, (dismissed or {})[field.id], shortage.fruit) then
                local planned = ADCropPlan.plannedFruit(field) or ""
                local value = ((yields or {})[planned] or 0) * ((prices or {})[planned] or 0)
                table.insert(candidates, {field = field, value = value})
            end
        end
        table.sort(candidates, function(a, b)
            if a.value ~= b.value then return a.value < b.value end
            local da, db = math.abs((a.field.areaHa or 0) - remaining), math.abs((b.field.areaHa or 0) - remaining)
            if da ~= db then return da < db end
            return a.field.id < b.field.id
        end)
        for _, candidate in ipairs(candidates) do
            if remaining <= 0 then break end
            local field = candidate.field
            local auto = field.chainFree == true and field.targetSource ~= "user"
            table.insert(actions, {fieldId = field.id, from = ADCropPlan.plannedFruit(field) or "", to = shortage.fruit,
                hectares = field.areaHa or 0, reason = shortage.fruit, mode = auto and "auto" or "suggest"})
            taken[field.id] = true
            remaining = remaining - (field.areaHa or 0)
        end
    end
    return actions
end