// PythonVenv is the path of the uv environment that will be created if use-virtualenv is true.
const PythnonUvVenvs = LocalLibPrefix + "/uv"

type PythonConfig struct {
	// Python binary to use when installing dependencies
	Version string `json:"version"`

	// Install requirements from given files
	Requirements RequirementsConfig `json:"requirements" validate:"omitempty,unique,dive"`

	UseSystemSitePackages Flag `json:"use-system-site-packages"`

	UseNoDepsFlag Flag `json:"no-deps"`

	// Use Poetry for package management
	Poetry PoetryConfig `json:"poetry"`

	//Use UV for package management
	Uv UvConfig `json:"uv"`

	// Specify a specific version of tox to install (T346226)
	ToxVersion string `json:"tox-version"`
}

// UvConfig holds configuration fields related to installation of project
// dependencies via UV package manager

type UvConfig struct {
	Version string `json:"version" validate:"omitempty,pypkgver"`
	Devel   Flag   `json:"devel"`
}

func (pc PythonConfig) InstructionsForPhase(phase build.Phase) []build.Instruction {
	ins := []build.Instruction{}

	if !pc.isEnabled() {
		return ins
	}

	// This only does something for build.PhasePreInstall
	ins = append(ins, pc.Requirements.InstructionsForPhase(phase)...)

	python := pc.version()

	switch phase {
	case build.PhasePreInstall:
		venvSetupCmd := []string{"-m", "venv", PythonVenv}
		if pc.UseSystemSitePackages.True {
			venvSetupCmd = append(venvSetupCmd, "--system-site-packages")
		}
		ins = append(ins, build.Run{python, venvSetupCmd})

		// "Activate" the virtualenv
		ins = append(ins, build.Env{map[string]string{
			"VIRTUAL_ENV": PythonVenv,
			"PATH":        PythonVenv + "/bin:$PATH",
		}})
		ins = append(ins, pc.setupPipAndPoetryAndUv()...)

		if pc.usePoetry() {
			cmd := []string{"install", "--no-root"}
			if !pc.Poetry.Devel.True {
				cmd = append(cmd, "--no-dev")
			}
			ins = append(ins, build.CreateDirectory(PythonPoetryVenvs))
			ins = append(ins, build.Run{"poetry", cmd})
		} else if pc.useUv() {
			cmd := []string{"sync"}
			if !pc.Uv.Devel.True {
				cmd = append(cmd, "--no-group", "dev")
			}
			ins = append(ins, build.CreateDirectory(PythnonUvVenvs))
			ins = append(ins, build.Run{"uv", cmd})
		} else {
			args := pc.RequirementsArgs()
			if args != nil {
				installCmd := []string{"-m", "pip", "install"}
				if pc.UseNoDepsFlag.True {
					installCmd = append(installCmd, "--no-deps")
				}
				ins = append(ins, build.Run{python, append(installCmd, args...)})
			}
		}

	case build.PhasePostInstall:
		if !pc.usePoetry() {
			if pc.UseNoDepsFlag.True {
				// Ensure requirements has all transitive dependencies
				ins = append(ins, build.Run{
					python, []string{
						"-m", "pip", "check",
					},
				})
			}
		}
	}

	return ins
}

func (pc PythonConfig) setupPipAndPoetryAndUv() []build.Instruction {
	ins := []build.Instruction{}

	ins = append(ins, build.RunAll{[]build.Run{
		{pc.version(), []string{"-m", "pip", "install", "-U", "setuptools!=60.9.0"}},
		{pc.version(), []string{"-m", "pip", "install", "-U", "wheel", pc.toxPackage(), pc.pipPackage()}},
	}})

	if pc.usePoetry() {
		ins = append(ins, build.Env{map[string]string{
			"POETRY_VIRTUALENVS_PATH": PythonPoetryVenvs,
		}})
		ins = append(ins, build.Run{
			pc.version(), []string{
				"-m", "pip", "install", "-U", "poetry" + pc.Poetry.Version,
			},
		})
	} else {
		ins = append(ins, build.Env{map[string]string{
			"UV_VIRTUALENVS_PATH": PythnonUvVenvs,
		}})
		ins = append(ins, build.Run{
			pc.version(), []string{
				"-m", "pip", "install", "-U", "uv" + pc.Uv.Version,
			},
		})
	}

	return ins
}

func (pc PythonConfig) useUv() bool {
	return pc.Uv.Version != ""
}