local hsluv = require("catppuccino.utils.hsluv")

local g = vim.g
local o = vim.o

local util = {}

util.bg = "#000000"
util.fg = "#ffffff"
util.day_brightness = 0.3

---@param hex_str string hexadecimal value of a color
local hex_to_rgb = function(hex_str)
    local hex = "[abcdef0-9][abcdef0-9]"
    local pat = "^#(" .. hex .. ")(" .. hex .. ")(" .. hex .. ")$"
    hex_str = string.lower(hex_str)

    assert(string.find(hex_str, pat) ~= nil, "hex_to_rgb: invalid hex_str: " .. tostring(hex_str))

    local red, green, blue = string.match(hex_str, pat)
    return {tonumber(red, 16), tonumber(green, 16), tonumber(blue, 16)}
end

---@param fg string foreground color
---@param bg string background color
---@param alpha number number between 0 and 1. 0 results in bg, 1 results in fg
function util.blend(fg, bg, alpha)
    bg = hex_to_rgb(bg)
    fg = hex_to_rgb(fg)

    local blendChannel = function(i)
        local ret = (alpha * fg[i] + ((1 - alpha) * bg[i]))
        return math.floor(math.min(math.max(0, ret), 255) + 0.5)
    end

    return string.format("#%02X%02X%02X", blendChannel(1), blendChannel(2), blendChannel(3))
end

function util.darken(hex, amount, bg)
    return util.blend(hex, bg or util.bg, math.abs(amount))
end

function util.lighten(hex, amount, fg)
    return util.blend(hex, fg or util.fg, math.abs(amount))
end

function util.brighten(color, percentage)
    local hsl = hsluv.hex_to_hsluv(color)
    local larpSpace = 100 - hsl[3]
    if percentage < 0 then
        larpSpace = hsl[3]
    end
    hsl[3] = hsl[3] + larpSpace * percentage
    return hsluv.hsluv_to_hex(hsl)
end

function util.invertColor(color)
    if color ~= "NONE" then
        local hsl = hsluv.hex_to_hsluv(color)
        hsl[3] = 100 - hsl[3]
        if hsl[3] < 40 then
            hsl[3] = hsl[3] + (100 - hsl[3]) * util.day_brightness
        end
        return hsluv.hsluv_to_hex(hsl)
    end
    return color
end

function util.string_to_color(colors, value, default)
    if not value or value == "" then
        return default
    end

    -- If the value is a hex color code then return it
    local hex = "[abcdef0-9][abcdef0-9]"
    local pat = "^#" .. hex .. hex .. hex .. "$"
    if string.match(value, pat) then
        return value
    end

    local acceptable_colors = {"black", "red", "green", "blue", "magenta", "cyan", "white", "orange", "pink"}
    for _, ac in ipairs(acceptable_colors) do
        if string.match(value, ac) then
            return colors[value]
        end
    end

    -- Did not match anything to return default
    return default
end

function util.highlight(group, color)
    local style = color.style and "gui=" .. color.style or "gui=NONE"
    local fg = color.fg and "guifg=" .. color.fg or "guifg=NONE"
    local bg = color.bg and "guibg=" .. color.bg or "guibg=NONE"
    local sp = color.sp and "guisp=" .. color.sp or ""
    local hl = "highlight " .. group .. " " .. style .. " " .. fg .. " " .. bg .. " " .. sp

    vim.cmd(hl)
    if color.link then
        vim.cmd("highlight! link " .. group .. " " .. color.link)
    end
end

function util.syntax(tbl)
    for group, colors in pairs(tbl) do
        if (type(group) == "number") then
            for inner_group, clrs in pairs(colors) do
                util.highlight(inner_group, clrs)
            end
        else
            util.highlight(group, colors)
        end
    end
end

function util.terminal(theme)
    g.terminal_color_0 = theme.colors.black
    g.terminal_color_1 = theme.colors.red
    g.terminal_color_2 = theme.colors.green
    g.terminal_color_3 = theme.colors.yellow
    g.terminal_color_4 = theme.colors.blue
    g.terminal_color_5 = theme.colors.magenta
    g.terminal_color_6 = theme.colors.cyan
    g.terminal_color_7 = theme.colors.white

    g.terminal_color_8 = theme.colors.black_br
    g.terminal_color_9 = theme.colors.red_br
    g.terminal_color_10 = theme.colors.green_br
    g.terminal_color_11 = theme.colors.yellow_br
    g.terminal_color_12 = theme.colors.blue_br
    g.terminal_color_13 = theme.colors.magenta_br
    g.terminal_color_14 = theme.colors.cyan_br
    g.terminal_color_15 = theme.colors.white_br
end

function util.load(theme)
    vim.cmd("hi clear")
    if vim.fn.exists("syntax_on") then
        vim.cmd("syntax reset")
    end

    o.background = "dark"
    o.termguicolors = true
    g.colors_name = "catppuccino"

    util.syntax(theme.base)
    util.syntax(theme.plugins)

    -- if opts.ui.terminal then
    --     util.terminal(theme)
    -- end
end

return util