local repo = require("git.core.repo")
local status = require("git.core.status")
local util = require("git.core.util")

local M = {}

---@class ow.Git.Statusline.Status
---@field head string?
---@field entry ow.Git.Status.Entry?

---@param entry ow.Git.Status.Entry?
---@return string
local function render(entry)
    if not entry then
        return ""
    end
    local marks = status.marks_for(entry)
    if #marks == 0 then
        return ""
    end
    local parts = {}
    for _, mark in ipairs(marks) do
        table.insert(
            parts,
            string.format("%%#%s#%s%%*", mark.hl, mark.char)
        )
    end
    return table.concat(parts, " ")
end

---@param buf integer
local function clear(buf)
    vim.b[buf].git_status = nil
    vim.b[buf].git_status_string = nil
end

---@param buf integer
---@param r ow.Git.Repo
---@param rel string
local function set_status(buf, r, rel)
    local entry = r:status_entry_for(rel)
    vim.b[buf].git_status = { head = r:head(), entry = entry }
    vim.b[buf].git_status_string = render(entry)
end

---@param buf integer
---@param r ow.Git.Repo?
local function update_buf(buf, r)
    if not vim.api.nvim_buf_is_valid(buf) then
        return
    end
    local name = vim.api.nvim_buf_get_name(buf)
    if name == "" or util.is_uri(name) then
        return clear(buf)
    end
    r = r or repo.find(buf)
    if not r then
        return clear(buf)
    end
    local rel = vim.fs.relpath(r.worktree, vim.fn.resolve(name))
    if not rel then
        return clear(buf)
    end
    set_status(buf, r, rel)
end

repo.on("change", function(r)
    local any_visible = false
    for buf in pairs(r.buffers) do
        if vim.api.nvim_buf_is_loaded(buf) then
            local name = vim.api.nvim_buf_get_name(buf)
            if name ~= "" and not util.is_uri(name) then
                local rel = vim.fs.relpath(r.worktree, vim.fn.resolve(name))
                if rel then
                    set_status(buf, r, rel)
                    if
                        not any_visible
                        and #vim.fn.win_findbuf(buf) > 0
                    then
                        any_visible = true
                    end
                end
            end
        end
    end
    if any_visible then
        vim.cmd.redrawstatus({ bang = true })
    end
end)

vim.api.nvim_create_autocmd("BufWinEnter", {
    group = vim.api.nvim_create_augroup("ow.git.statusline", { clear = true }),
    callback = function(args)
        update_buf(args.buf, nil)
    end,
})

for _, buf in ipairs(vim.api.nvim_list_bufs()) do
    if vim.api.nvim_buf_is_loaded(buf) then
        update_buf(buf, nil)
    end
end

return M