local util = require("git.util")

local M = {}

local BUF_NAME = "githistory://log"

---@type integer?
local cached_buf

---@return integer
local function get_buf()
    if cached_buf and vim.api.nvim_buf_is_valid(cached_buf) then
        return cached_buf
    end
    local buf = vim.api.nvim_create_buf(false, true)
    pcall(vim.api.nvim_buf_set_name, buf, BUF_NAME)
    util.setup_scratch(buf, { bufhidden = "hide" })
    cached_buf = buf
    return buf
end

---@param args string[]
---@param lines string[]
function M.append(args, lines)
    if #lines == 0 then
        return
    end
    local buf = get_buf()
    local count = vim.api.nvim_buf_line_count(buf)
    local first = vim.api.nvim_buf_get_lines(buf, 0, 1, false)[1] or ""
    local empty = count == 1 and first == ""
    local payload = { "$ git " .. table.concat(args, " ") }
    vim.list_extend(payload, lines)
    vim.bo[buf].modifiable = true
    if empty then
        vim.api.nvim_buf_set_lines(buf, 0, -1, false, payload)
    else
        table.insert(payload, 1, "")
        vim.api.nvim_buf_set_lines(buf, count, count, false, payload)
    end
    vim.bo[buf].modifiable = false
    vim.bo[buf].modified = false
end

function M.open()
    local buf = get_buf()
    local win = vim.fn.bufwinid(buf)
    if win ~= -1 then
        vim.api.nvim_set_current_win(win)
    else
        util.place_buf(buf, nil)
        win = vim.api.nvim_get_current_win()
    end
    local last = vim.api.nvim_buf_line_count(buf)
    vim.api.nvim_win_set_cursor(win, { last, 0 })
end

return M