// Copyright IBM Corp. 2014, 2026
// SPDX-License-Identifier: BUSL-1.1

package command

import (
	"log"
	"os"

	"github.com/hashicorp/terraform/internal/depsfile"
	"github.com/hashicorp/terraform/internal/tfdiags"
)

// dependenclyLockFilename is the filename of the dependency lock file.
//
// This file should live in the same directory as the .tf files for the
// root module of the configuration, alongside the .terraform directory
// as long as that directory's path isn't overridden by the TF_DATA_DIR
// environment variable.
//
// We always expect to find this file in the current working directory
// because that should also be the root module directory.
//
// Some commands have legacy command line arguments that make the root module
// directory something other than the root module directory; when using those,
// the lock file will be written in the "wrong" place (the current working
// directory instead of the root module directory) but we do that intentionally
// to match where the ".terraform" directory would also be written in that
// case. Eventually we will phase out those legacy arguments in favor of the
// global -chdir=... option, which _does_ preserve the intended invariant
// that the root module directory is always the current working directory.
const dependencyLockFilename = ".terraform.lock.hcl"

// lockedDependencies reads the dependency lock information from the lock file
// in the current working directory.
//
// If the lock file doesn't exist at the time of the call, lockedDependencies
// indicates success and returns an empty Locks object. If the file does
// exist then the result is either a representation of the contents of that
// file at the instant of the call or error diagnostics explaining some way
// in which the lock file is invalid.
//
// The result is a snapshot of the locked dependencies at the time of the call
// and does not update as a result of calling replaceLockedDependencies
// or any other modification method.
func (m *Meta) lockedDependencies() (*depsfile.Locks, tfdiags.Diagnostics) {
	// We check that the file exists first, because the underlying HCL
	// parser doesn't distinguish that error from other error types
	// in a machine-readable way but we want to treat that as a success
	// with no locks. There is in theory a race condition here in that
	// the file could be created or removed in the meantime, but we're not
	// promising to support two concurrent dependency installation processes.
	_, err := os.Stat(dependencyLockFilename)
	if os.IsNotExist(err) {
		return m.annotateDependencyLocksWithOverrides(depsfile.NewLocks()), nil
	}

	ret, diags := depsfile.LoadLocksFromFile(dependencyLockFilename)
	return m.annotateDependencyLocksWithOverrides(ret), diags
}

// replaceLockedDependencies creates or overwrites the lock file in the
// current working directory to contain the information recorded in the given
// locks object.
func (m *Meta) replaceLockedDependencies(new *depsfile.Locks) tfdiags.Diagnostics {
	return depsfile.SaveLocksToFile(new, dependencyLockFilename)
}

// mergeLockedDependencies combines two sets of locks. The 'base' locks are copied, and any providers
// present in the additional locks that aren't present in the base are added to that copy. The merged
// combination is returned.
//
// If you're combining locks derived from config with other locks (from state or deps locks file), then
// the config locks need to be the first argument to ensure that the merged locks contain any
// version constraints. Version constraint data is only present in configuration.
// This allows code in the init command to download providers in separate phases and
// keep the lock file updated accurately after each phase.
//
// This method supports downloading providers in 2 steps, and is used during the second download step and
// while updating the dependency lock file.
func (m *Meta) mergeLockedDependencies(baseLocks, additionalLocks *depsfile.Locks) *depsfile.Locks {
	var mergedLocks *depsfile.Locks
	if baseLocks != nil {
		mergedLocks = baseLocks.DeepCopy()
	} else {
		mergedLocks = depsfile.NewLocks()
	}

	// Append locks derived from the state to locks derived from config.
	for _, lock := range additionalLocks.AllProviders() {
		match := mergedLocks.Provider(lock.Provider())
		if match != nil {
			log.Printf("[TRACE] Ignoring provider %s version %s in appendLockedDependencies; lock file contains %s version %s already",
				lock.Provider(),
				lock.Version(),
				match.Provider(),
				match.Version(),
			)
		} else {
			// This is a new provider now present in the lockfile yet
			log.Printf("[DEBUG] Appending provider %s to the lock file", lock.Provider())
			mergedLocks.SetProvider(lock.Provider(), lock.Version(), lock.VersionConstraints(), lock.AllHashes())
		}
	}

	// Override the locks file with the new combination of locks
	return mergedLocks
}

// annotateDependencyLocksWithOverrides modifies the given Locks object in-place
// to track as overridden any provider address that's subject to testing
// overrides, development overrides, or "unmanaged provider" status.
//
// This is just an implementation detail of the lockedDependencies method,
// not intended for use anywhere else.
func (m *Meta) annotateDependencyLocksWithOverrides(ret *depsfile.Locks) *depsfile.Locks {
	if ret == nil {
		return ret
	}

	for addr := range m.ProviderDevOverrides {
		log.Printf("[DEBUG] Provider %s is overridden by dev_overrides", addr)
		ret.SetProviderOverridden(addr)
	}
	for addr := range m.UnmanagedProviders {
		log.Printf("[DEBUG] Provider %s is overridden as an \"unmanaged provider\"", addr)
		ret.SetProviderOverridden(addr)
	}
	if m.testingOverrides != nil {
		for addr := range m.testingOverrides.Providers {
			log.Printf("[DEBUG] Provider %s is overridden in Meta.testingOverrides", addr)
			ret.SetProviderOverridden(addr)
		}
	}

	return ret
}
