---@class ow.Git.Revision
---@field stage 0|1|2|3?
---@field path string?
---@field base string?
local Revision = {}
Revision.__index = Revision

local URI_PREFIX = "git://"

---@return string
function Revision:format()
    if self.stage then
        return ":" .. self.stage .. ":" .. self.path
    elseif self.path then
        return self.base .. ":" .. self.path
    end
    return self.base or error("Revision:format: empty Revision")
end

---@return string
function Revision:uri()
    return URI_PREFIX .. self:format()
end

---@param parts { stage?: integer, base?: string, path?: string }
---@return ow.Git.Revision
function Revision.new(parts)
    return setmetatable(parts, Revision)
end

---@param str string
---@return ow.Git.Revision
function Revision.parse(str)
    local stage, path = str:match("^:([0123]):(.+)$")
    if stage then
        return Revision.new({
            stage = tonumber(stage) --[[@as (0|1|2|3)?]],
            path = path,
        })
    end
    path = str:match("^:([^:]+)$")
    if path then
        return Revision.new({ stage = 0, path = path })
    end
    local base, p = str:match("^([^:]+):(.+)$")
    if base then
        return Revision.new({ base = base, path = p })
    end
    return Revision.new({ base = str })
end

---@param str string
---@return ow.Git.Revision?
function Revision.from_uri(str)
    local raw = str:match("^" .. URI_PREFIX .. "(.+)$")
    if raw then
        return Revision.parse(raw)
    end
end

return Revision