-- mod-version:2
local command = require "core.command"
local common = require "core.common"
local config = require "core.config"
local style = require "core.style"
local DocView = require "core.docview"

-- General plugin settings
config.plugins.minimap = {
	enabled = true,
	width = 100,
	instant_scroll = false,
	syntax_highlight = true,
	scale = 1,
	-- how many spaces one tab is equivalent to
	tab_width = 4,
	draw_background = true
}

-- Configure size for rendering each char in the minimap
local char_height = 1 * SCALE * config.plugins.minimap.scale
local char_spacing = 0.8 * SCALE * config.plugins.minimap.scale
local line_spacing = 2 * SCALE * config.plugins.minimap.scale

-- Overloaded since the default implementation adds a extra x3 size of hotspot for the mouse to hit the scrollbar.
local prev_scrollbar_overlaps_point = DocView.scrollbar_overlaps_point
DocView.scrollbar_overlaps_point = function(self, x, y)
	if not config.plugins.minimap.enabled then
		return prev_scrollbar_overlaps_point(self, x, y)
	end

	local sx, sy, sw, sh = self:get_scrollbar_rect()
	return x >= sx and x < sx + sw and y >= sy and y < sy + sh
end

-- Helper function to determine if current file is too large to be shown fully inside the minimap area.
local function is_file_too_large(self)
	local line_count = #self.doc.lines
	local _, _, _, sh = self:get_scrollbar_rect()

	-- check if line count is too large to fit inside the minimap area
	local max_minmap_lines = math.floor(sh / line_spacing)
	return line_count > 1 and line_count > max_minmap_lines
end

-- Overloaded with an extra check if the user clicked inside the minimap to automatically scroll to that line.
local prev_on_mouse_pressed = DocView.on_mouse_pressed
DocView.on_mouse_pressed = function(self, button, x, y, clicks)
	if not config.plugins.minimap.enabled then
		return prev_on_mouse_pressed(self, button, x, y, clicks)
	end

	-- check if user clicked in the minimap area and jump directly to that line
	-- unless they are actually trying to perform a drag
	local minimap_hit = self:scrollbar_overlaps_point(x, y)
	if minimap_hit then
		local line_count = #self.doc.lines
		local minimap_height = line_count * line_spacing

		-- check if line count is too large to fit inside the minimap area
		local is_too_large = is_file_too_large(self)
		if is_too_large then
			local _, _, _, sh = self:get_scrollbar_rect()
			minimap_height = sh
		end

		-- calc which line to jump to
		local dy = y - self.position.y
		local jump_to_line = math.floor((dy / minimap_height) * line_count) + 1

		local _, cy, _, cy2 = self:get_content_bounds()
		local lh = self:get_line_height()
		local visible_lines_count = math.max(1, (cy2 - cy) / lh)
		local visible_lines_start = math.max(1, math.floor(cy / lh))

		-- calc if user hit the currently visible area
		local hit_visible_area = true
		if is_too_large then

			local visible_height = visible_lines_count * line_spacing
			local scroll_pos = (visible_lines_start - 1) /
							                   (line_count - visible_lines_count - 1)
			scroll_pos = math.min(1.0, scroll_pos) -- 0..1
			local visible_y = self.position.y + scroll_pos *
							                  (minimap_height - visible_height)

			local t = (line_count - visible_lines_start) / visible_lines_count
			if t <= 1 then visible_y = visible_y + visible_height * (1.0 - t) end

			if y < visible_y or y > visible_y + visible_height then
				hit_visible_area = false
			end
		else

			-- If the click is on the currently visible line numbers,
			-- ignore it since then they probably want to initiate a drag instead.
			if jump_to_line < visible_lines_start or jump_to_line > visible_lines_start +
							visible_lines_count then hit_visible_area = false end
		end

		-- if user didn't click on the visible area (ie not dragging), scroll accordingly
		if not hit_visible_area then
			self:scroll_to_line(jump_to_line, false, config.plugins.minimap.instant_scroll)
		end

	end

	return prev_on_mouse_pressed(self, button, x, y, clicks)
end

-- Overloaded with pretty much the same logic as original DocView implementation,
-- with the exception of the dragging scrollbar delta. We want it to behave a bit snappier
-- since the "scrollbar" essentially represents the lines visible in the content view.
local prev_on_mouse_moved = DocView.on_mouse_moved
DocView.on_mouse_moved = function(self, x, y, dx, dy)
	if not config.plugins.minimap.enabled then
		return prev_on_mouse_moved(self, x, y, dx, dy)
	end

	if self.dragging_scrollbar then
		local line_count = #self.doc.lines
		local lh = self:get_line_height()
		local delta = lh / line_spacing * dy

		if is_file_too_large(self) then
			local _, sy, _, sh = self:get_scrollbar_rect()
			delta = (line_count * lh) / sh * dy
		end

		self.scroll.to.y = self.scroll.to.y + delta
	end

	-- we need to "hide" that the scrollbar is dragging so that View doesnt does its own scrolling logic
	local t = self.dragging_scrollbar
	self.dragging_scrollbar = false
	local r = prev_on_mouse_moved(self, x, y, dx, dy)
	self.dragging_scrollbar = t
	return r
end

-- Overloaded since we want the mouse to interact with the full size of the minimap area,
-- not juse the scrollbar.
local prev_get_scrollbar_rect = DocView.get_scrollbar_rect
DocView.get_scrollbar_rect = function(self)
	if not config.plugins.minimap.enabled then return prev_get_scrollbar_rect(self) end

	return self.position.x + self.size.x - config.plugins.minimap.width * SCALE,
	       self.position.y, config.plugins.minimap.width * SCALE, self.size.y
end

-- Overloaded so we can render the minimap in the "scrollbar area".
local prev_draw_scrollbar = DocView.draw_scrollbar
DocView.draw_scrollbar = function(self)
	if not config.plugins.minimap.enabled then return prev_draw_scrollbar(self) end

	local x, y, w, h = self:get_scrollbar_rect()

	local highlight = self.hovered_scrollbar or self.dragging_scrollbar
	local visual_color = highlight and style.scrollbar2 or style.scrollbar

	local _, cy, _, cy2 = self:get_content_bounds()
	local lh = self:get_line_height()
	local visible_lines_count = math.max(1, (cy2 - cy) / lh)
	local visible_lines_start = math.max(1, math.floor(cy / lh))
	local scroller_height = visible_lines_count * line_spacing
	local line_count = #self.doc.lines

	local visible_y = self.position.y + (visible_lines_start - 1) * line_spacing

	-- check if file is too large to fit inside the minimap area
	local max_minmap_lines = math.floor(h / line_spacing)
	local minimap_start_line = 1
	if is_file_too_large(self) then

		local scroll_pos = (visible_lines_start - 1) /
						                   (line_count - visible_lines_count - 1)
		scroll_pos = math.min(1.0, scroll_pos) -- 0..1, procent of visual area scrolled

		local scroll_pos_pixels = scroll_pos * (h - scroller_height)
		visible_y = self.position.y + scroll_pos_pixels

		-- offset visible area if user is scrolling past end
		local t = (line_count - visible_lines_start) / visible_lines_count
		if t <= 1 then visible_y = visible_y + scroller_height * (1.0 - t) end

		minimap_start_line = visible_lines_start -
						                     math.floor(scroll_pos_pixels / line_spacing)
		minimap_start_line = math.max(1, math.min(minimap_start_line,
		                                          line_count - max_minmap_lines))
	end

	if config.plugins.minimap.draw_background then
		renderer.draw_rect(x, y, w, h, style.minimap_background or style.background)
	end
	-- draw visual rect
	renderer.draw_rect(x, visible_y, w, scroller_height, visual_color)

	-- time to draw the actual code, setup some local vars that are used in both highlighted and plain renderind.
	local line_y = y

	-- when not using syntax highlighted rendering, just use the normal color but dim it 50%.
	local color = style.syntax["normal"]
	color = {color[1], color[2], color[3], color[4] * 0.5}

	-- we try to "batch" characters so that they can be rendered as just one rectangle instead of one for each.
	local batch_width = 0
	local batch_start = x
	local minimap_cutoff_x = x + config.plugins.minimap.width * SCALE
	local batch_syntax_type = nil
	local function flush_batch(type)
		local old_color = color
		color = style.syntax[batch_syntax_type]
		if config.plugins.minimap.syntax_highlight and color ~= nil then
			-- fetch and dim colors
			color = {color[1], color[2], color[3], color[4] * 0.5}
		else
			color = old_color
		end
		if batch_width > 0 then
			renderer.draw_rect(batch_start, line_y, batch_width, char_height, color)
		end
		batch_syntax_type = type
		batch_start = batch_start + batch_width
		batch_width = 0
	end

	-- render lines with syntax highlighting
	if config.plugins.minimap.syntax_highlight then

		-- keep track of the highlight type, since this needs to break batches as well
		batch_syntax_type = nil

		-- per line
		local endidx = minimap_start_line + max_minmap_lines
		endidx = math.min(endidx, line_count)
		for idx = minimap_start_line, endidx do
			batch_syntax_type = nil
			batch_start = x
			batch_width = 0

			-- per token
			for _, type, text in self.doc.highlighter:each_token(idx) do
				-- flush prev batch
				if not batch_syntax_type then batch_syntax_type = type end
				if batch_syntax_type ~= type then flush_batch(type) end

				-- per character
				for char in common.utf8_chars(text) do
					if char == " " or char == "\n" then
						flush_batch(type)
						batch_start = batch_start + char_spacing
					elseif char == "	" then
						flush_batch(type)
						batch_start = batch_start + (char_spacing * config.plugins.minimap.tab_width)
					elseif batch_start + batch_width > minimap_cutoff_x then
						flush_batch(type)
						break
					else
						batch_width = batch_width + char_spacing
					end

				end
			end
			flush_batch(nil)
			line_y = line_y + line_spacing
		end

	else -- render lines without syntax highlighting
		for idx = 1, line_count - 1 do
			batch_start = x
			batch_width = 0

			for char in common.utf8_chars(self.doc.lines[idx]) do
				if char == " " or char == "\n" then
					flush_batch()
					batch_start = batch_start + char_spacing
				elseif batch_start + batch_width > minimap_cutoff_x then
					flush_batch()
				else
					batch_width = batch_width + char_spacing
				end
			end
			flush_batch()
			line_y = line_y + line_spacing
		end

	end

end

local prev_update = DocView.update
DocView.update = function (self)
	if not config.plugins.minimap.enabled then return prev_update(self) end
	self.size.x = self.size.x - config.plugins.minimap.width * SCALE
	return prev_update(self)
end

command.add(nil, {
	["minimap:toggle-visibility"] = function()
		config.plugins.minimap.enabled = not config.plugins.minimap.enabled
	end,
	["minimap:toggle-syntax-highlighting"] = function()
		config.plugins.minimap.syntax_highlight = not config.plugins.minimap.syntax_highlight
	end
})