local p = {}
local args = {}

local data_module_prefix = "Module:Solar eclipse/db/"
local infobox_image = nil -- lazy load

local function InfoboxImage(image)
	if (image and image ~= '') then
		if infobox_image == nil then
			infobox_image = require('Module:InfoboxImage').InfoboxImage
		end
		return infobox_image{args = {
			image = image,
				size = '320px',
				sizedefault = 'frameless',
				upright = 1
		}}
	end
	return nil
end

local function ifnotempty(s, a, b)
    return (s and s ~= '') and a or b
end

local function ifexist(page)
	if not page then return false end
	if mw.title.new(page).exists then return true end
	return false
end

local function parsedate(y, m, d)
    local lang = mw.language.getContentLanguage()
    d = string.format("%02d", tonumber(d))
    m = string.format("%02d", tonumber(m))
    local date_str = y .. '-' .. m .. '-' .. d
    local success, result = pcall(lang.formatDate, lang, 'F j, Y', date_str)
    return success and result or date_str
end

local function parsecoord(frame, s)
    local lat, NS, lon, EW = s:match('^%s*(%d+%.?%d*)%s*([NS])%s*(%d+%.?%d*)%s*([EW])%s*$')
    if lat and NS and lon and EW then
        return frame:expandTemplate{
            title = 'coord',
            args = {lat, NS, lon, EW, 'type:landmark'}
        }
    end
    return s
end

local function parsekm(frame, s)
	if(s and s:match('^%s*[%d][%d.]*%s*$')) then
		return frame:expandTemplate{ title = 'convert', args = {s, 'km', 'mi', abbr = 'on'} }
	else
		if(s and s ~= '') then
			return s .. ' km'
		else
			return nil
		end
	end
end

local function parsetime(s)
	if(s and s ~= '') then
		local min = s:match('^%s*(%d+)m%s*%d+s%s*$')
		local sec = s:match('^%s*%d+m%s*(%d+)s%s*$')
		if( min and sec ) then
			return tostring(tonumber(min)*60 + tonumber(sec)) .. ' s' ..
				' (' .. min .. ' min ' .. sec .. ' s)'
		end
	end
	return s
end

local function cataloglink(c, y, m, d)
	y, m, d = tonumber(y), tonumber(m), tonumber(d)
	if tonumber(c) and y and m and d then
		d = (d < 10) and ('0' .. d) or d
		m = (m < 10) and ('0' .. m) or m
		return '[https://eclipse.gsfc.nasa.gov/SEsearch/SEdata.php?Ecl=+' .. y .. m .. d .. ' ' .. c .. ']'
	else
		return c
	end
end

local function createLink(label, suffix)
    if not label or label == '' then
        return ''
    end

    local prefix = "Solar eclipse of "
    -- check if label starts with the prefix
    if mw.ustring.find(label, "^" .. prefix) then
        -- extract the date part from the label
        local dateLabel = mw.ustring.sub(label, #prefix + 1)
        local page = label -- this is the full page title to link to

        if ifexist(page) then
            return string.format('[[%s|%s]]', page, dateLabel)
        else
            -- if page doesn't exist, display the date
            return dateLabel
        end
    else
        -- if the label is a a link, keep it
        if mw.ustring.match(label, "^%[%[.*%]%]$") then
            return label
        else
            -- for labels without the prefix, display as plain text
            return label
        end
    end
end

local function loadsolardb(frame, s)
	local yearstr = s:match('^%s*(%d%d%d%d)[A-Z][a-z][a-z]%d%d%s*$') or ''
	local function setarg(k, v)
		if(v and v ~= '') then
			v = mw.ustring.gsub(v, '^%s*%-(%d)', '−%1')
			args[k] = v
		end
	end
	if( yearstr ~= '' ) then
		local dbsubpage = math.floor( (tonumber(yearstr) - 1) / 50 ) * 5
		local dbpage  = data_module_prefix .. tostring( dbsubpage )
		if (ifexist(dbpage)) then
			local data = mw.loadData(dbpage)
			local dargs = data[s] or error('Error: unknown date ' .. s .. ' in Infobox solar eclipse' , 0)
			setarg('date', parsedate(dargs['y'], dargs['m'] or dargs['m3'] or dargs['m2'], dargs['d'] or dargs['d2']))
			setarg('image', (dargs['Ph'] and dargs['Ph'] ~= '') and '[[File:' .. dargs['Ph']  .. '|320px]]' or nil)
			setarg('caption', dargs['PhCap'])
			setarg('map', (dargs['Map'] and dargs['Map'] ~= '') and '[[File:' .. dargs['Map']  .. '|320px]]' or nil)
			setarg('map_caption', 'Map')
			setarg('type_ref', '')
			setarg('cat', cataloglink(dargs['Cat'], dargs['y'], dargs['m'] or dargs['m3'] or dargs['m2'], dargs['d'] or dargs['d2']) )
			setarg('nature', dargs['Ty'])
			setarg('gamma', dargs['Gam'])
			setarg('magnitude', dargs['Mag'])
			setarg('saros', dargs['Saros'] and '[[Solar Saros ' .. dargs['Saros'] .. '|'  .. dargs['Saros'] .. ']]')
			setarg('saros_sequence', dargs['Mem'])
			setarg('saros_total', dargs['Max'])
			setarg('max_eclipse_ref', '')
			setarg('duration', parsetime(dargs['Dur']))
			setarg('location', '')
			setarg('coords', parsecoord(frame,dargs['Loc']))
			setarg('max_width', parsekm(frame,dargs['Wid']))
			setarg('times_ref', '')
			setarg('start_partial', dargs['TiPB'])
			setarg('start_total', dargs['TiTB'])
			setarg('start_central', '')
			setarg('greatest_eclipse', dargs['TiG'])
			setarg('end_central', '')
			setarg('end_total', dargs['TiTE'])
			setarg('end_partial', dargs['TiPE'])
			setarg('previous', '')
			setarg('next', '')
		end
	end
end

local function infobox(frame)
	local titlestr = ifnotempty(args['date'],
		"Solar eclipse of " .. (args['date'] or ''),
		"For instructions on use, see [[Template:Infobox Solar eclipse]]")
	local bgcolor = args['background'] or args['bgcolour'] or ''
	local mapstr = ifnotempty(args['map'],
		"<div style='padding-bottom:0.5em;'>" ..
		(InfoboxImage(args['map']) or '') .. ifnotempty(args['map_caption'],
			"<div style='line-height:1.2em; padding-top:0.1em;'>" ..
			(args['map_caption'] or '') .. "</div>", '') .. '</div>')
		
	local prevLink = createLink(args['previous'], 'solar eclipse')
	local nextLink = createLink(args['next'], 'solar eclipse')
	local belowstr = ''
	if prevLink ~= '' and nextLink ~= '' then
		belowstr = string.format('<div style="width:100%%"><div class="noprint" style="float:left">← %s</div><div class="noprint" style="float:right">%s →</div></div>', 
			prevLink, nextLink)
	elseif prevLink ~= '' then
		belowstr = string.format('<div style="width:100%%"><div class="noprint" style="text-align:left">← %s</div></div>', prevLink)
	elseif nextLink ~= '' then
		belowstr = string.format('<div style="width:100%%"><div class="noprint" style="text-align:right">%s →</div></div>', nextLink)
	end
	
	local eclipse_types = {
    	total   = { label = "'''Total eclipse'''",   color = "#690005" },
    	partial = { label = "'''Partial eclipse'''", color = "#854739" },
    	annular = { label = "'''Annular eclipse'''", color = "#4C4CB1" },
    	hybrid  = { label = "'''Hybrid eclipse'''",  color = "#006600" }
	}
	
	local nature = args['nature'] and args['nature']:lower() or ''
	local eclipse_config = eclipse_types[nature] or { label = "Eclipse", color = "#727272" }
	local type_header = string.format(
    	'<span style="background-color: %s; color: white; display: block;">%s</span>',
    	eclipse_config.color,
    	eclipse_config.label
    )


	return frame:expandTemplate{ title = 'infobox', args = {
		["bodyclass"] = "vevent",
		["bodystyle"] = "width:25em; text-align:left; font-size:88%;",
		["title"] = titlestr,
		["subheader"] = type_header,
		["below"] = belowstr,
		["belowstyle"] = "text-align:center; padding-top:0.5em",
------------------ Images and maps ------------------
		["image"] = InfoboxImage(args['image']),
		["imagestyle"] = "padding-bottom:0.5em;",
		["caption"] = args['caption'] or '',
		["headerstyle"] = "background:#eee; color:inherit; font-size:105%;",
		["data1"] = mapstr,
------------- Type of eclipse and saros -------------
		["label4"]  = "[[Gamma (eclipse)|Gamma]]",
		["data4"]   = args['gamma'] or '',
		["label5"]  = "[[Magnitude of eclipse|Magnitude]]",
		["data5"]   = args['magnitude'] or '',
------------------ Maximum eclipse ------------------
		["header7"] = "Maximum eclipse" .. (args['max_eclipse_ref'] or ''),
		["label8"] = "Duration",
		["data8"] = args['duration'] or '',
		["label9"] = "Location",
		["data9"] = args['location'] or '',
		["class9"] = "location",
		["label10"] = "Coordinates",
		["data10"] = args['coords'] or '',
		["label11"] = "Max.&nbsp;width of&nbsp;band",
		["data11"] = args['max_width'] or '',
----------------------- Times -----------------------
		["header12"] = "Times ([[UTC]])" .. (args['times_ref'] or ''),
		["label13"] = "(P1) Partial begin",
		["data13"] = args['start_partial'] or '',
		["label14"] = "(U1) Total begin",
		["data14"] = args['start_total'] or '',
		["label15"] = "(U2) Central begin",
		["data15"] = args['start_central'] or '',
		["label16"] = "Greatest eclipse",
		["data16"] = args['greatest_eclipse'] or '',
		["label17"] = "(U3) Central end",
		["data17"] = args['end_central'] or '',
		["label18"] = "(U4) Total end",
		["data18"] = args['end_total'] or '',
		["label19"] = "(P4) Partial end",
		["data19"] = args['end_partial'] or '',
------------------------ Event references -------------------------
		["header20"] = "References",
		["label21"] = "[[Saros (astronomy)|Saros]]",
		["data21"] = (args['saros'] or '')
			.. " (" .. (args['saros_sequence'] or '') .. " of " .. (args['saros_total'] or '') .. ")",
		["label22"] = "Catalog # (SE5000)",
		["data22"] = args['cat'] or '',
		} }

end

function p.box(frame)
	args = require('Module:Arguments').getArgs(frame, {
			wrappers = 'Template:Infobox solar eclipse'
		})

	if( args['2'] and args['2'] ~= '') then
		loadsolardb(frame,args['2'])
	elseif( args['1'] and args['1'] ~= '') then
		loadsolardb(frame,args['1'])
	end
	
	return infobox(frame)
end

return p