-- TODO:         show current hunk in status line
-- TODO:         incorporate more patchutils functionality

-- FIXME https://www.reddit.com/r/neovim/comments/unwvkw/github_hkuptyrunesnvim_lua_test_framework_for/
-- FIXME https://github.com/hkupty/runes.nvim

pretty = require("pl.pretty")

local M = {}

-- Header object
M.Header = {}

function M.Header:parse(lineNo)
    local inline
    local pat = "@@%s+%-(%d+),(%d+)%s+%+(%d+),(%d+)%s+@@%s*(.*)"

    if (lineNo == "." or type(lineNo) == "number") then
        -- to convert lineNo into proper number, if it was "." originally
        inline, lineNo = M.getline(lineNo)
    else
        inline = lineNo
        lineNo = 0
    end

    local of, oc, nf, nc, rem = inline:match(pat)

    return {
        line = lineNo,
        oldFirst = tonumber(of),
        oldCount = tonumber(oc),
        newFirst = tonumber(nf),
        newCount = tonumber(nc),
        remainderLine = rem
    }
end

-- Generate hunk header line
-- TODO some protection against bad parameters (creating impossible regions of lines)
-- TODO return empty string in such case
function M.createHunkHeader(oldStart, oldLen, newStart, newLen, remaind)
    return "@@ -" .. oldStart .. "," .. oldLen ..
        " +" .. newStart .. "," .. newLen .. " @@ " .. remaind
end

-- Compatibility shim for getline()
function M.getline(where, endWhere)
    if vis ~= nil then
        local win = vis.win
        local line = where

        if where == "." then
          line = win.selection.line
        end
        if endWhere == nil then
            return win.file.lines[line], line
        end

        -- now endWhere ~= nil and we need to return an array
        local out = {}
        for i=line, endWhere do
            table.insert(out, win.file.lines[i])
        end

        return out, line
    else
        return vim.fn.getline(where), vim.fn.line(where)
    end
 end


-- Return number of lines in the range between start and end line (both
-- inclusive) which are from the state before patch and the one after
-- patch is applied.
function M.countLines(start, endline)
    local context_lines = 0
    local old_lines = 0
    local new_lines = 0

    for line, _ in pairs(M.getline(start, endline)) do
        local first_char = line:sub(1, 1)
        if first_char == ' ' then
            local context_lines = context_lines + 1
        elseif first_char == '-' then
            local old_lines = old_lines + 1
        elseif first_char == '+' then
            local new_lines = new_lines + 1
        end
    end

    return {context_lines + old_lines, context_lines + new_lines}
end

return M