package meshcatalogclient

import (
	"encoding/json"
	"fmt"
	"path"
	"strings"

	seat "git.novox.be/novox/mesh-delivery/contracts/go/seats/meshcatalog"
	"git.novox.be/novox/mesh-sdk/go/keys"
)

// RootPath is a `modules` value's path when the module's manifest is its repository's root.
const RootPath = "."

// SourcePrefix1 opens the fingerprint of the old form a `modules` value may still carry in `fp`.
const SourcePrefix1 = "src1:"

// ModulesKey is the key of a `modules` value: the module's name.
func ModulesKey(module string) (string, error) {
	if err := keys.CheckName("module", module); err != nil {
		return "", err
	}
	return seat.ModulesByModuleKey(module), nil
}

// ParseModulesKey is the inverse of ModulesKey.
func ParseModulesKey(key string) (string, error) {
	module, err := ModulesKey(key)
	if err != nil {
		return "", fmt.Errorf("meshcatalogclient: %q is not a modules key: %w", key, err)
	}
	return module, nil
}

// CheckModule refuses a `modules` value that contradicts itself: both or neither of a fingerprint and the reason for none,
// of either form, an old fingerprint not of the form `src1:`, kept inputs without a manifest digest, a verdict the indexer
// does not write, problems without a refusal (or a refusal without problems), a path that is not clean inside the module's
// directory, and a fingerprint or a digest not of its form.
func CheckModule(m seat.ModulesByModuleValue) error {
	switch {
	case m.Fp != "" && m.None != "":
		return fmt.Errorf("meshcatalogclient: a module has both a fingerprint and a reason for none")
	case m.Fp == "" && m.None == "" && m.Fp2 == "" && m.None2 == "":
		return fmt.Errorf("meshcatalogclient: a module has neither a fingerprint nor a reason for none, of either form")
	case m.Fp != "" && !strings.HasPrefix(m.Fp, SourcePrefix1):
		return fmt.Errorf("meshcatalogclient: the module's fingerprint %q does not start with %s", m.Fp, SourcePrefix1)
	case m.Fp2 != "" && m.None2 != "":
		return fmt.Errorf("meshcatalogclient: a module has both fp2 and none2")
	}
	for language, t := range m.Toolchains {
		if t.Version == "" || t.Recipe == "" {
			return fmt.Errorf("meshcatalogclient: the module's toolchain of %q needs its version and its recipe version", language)
		}
	}
	if m.Inputs2 != nil && m.Manifest == "" {
		return fmt.Errorf("meshcatalogclient: a module keeps new-form inputs but has no manifest digest")
	}
	for artifact, paths := range m.Paths {
		if artifact == "" || len(paths) == 0 {
			return fmt.Errorf("meshcatalogclient: the module's named paths of the artifact %q are empty or name no artifact", artifact)
		}
		for _, p := range paths {
			if !cleanInside(p) {
				return fmt.Errorf("meshcatalogclient: the artifact %q names the path %q, not a clean path inside the module's directory", artifact, p)
			}
		}
	}
	if in := m.Inputs2; in != nil {
		if f := in.ImportForm; f != "" && (len(in.Imports) == 0 || !strings.HasPrefix(f, SourcePrefix2) || !keys.IsHex64(f[len(SourcePrefix2):])) {
			return fmt.Errorf("meshcatalogclient: the kept import form %q is set only with imports, and is %s and 64 hex digits", f, SourcePrefix2)
		}
		for p, object := range in.Paths {
			if !cleanInside(p) {
				return fmt.Errorf("meshcatalogclient: the named path %q is not a clean path inside the module's directory", p)
			}
			if object == "" {
				return fmt.Errorf("meshcatalogclient: the named path %q names no git object", p)
			}
		}
	}
	switch {
	case m.Verdict != "" && m.Verdict != VerdictAccepted && m.Verdict != VerdictRefused:
		return fmt.Errorf("meshcatalogclient: the module's verdict %q is neither %s nor %s", m.Verdict, VerdictAccepted, VerdictRefused)
	case len(m.Unknown) > 0 && m.Verdict != VerdictRefused:
		return fmt.Errorf("meshcatalogclient: a module's unknown fields are named only with the refusal a wait is written as")
	case m.Verdict != "" && m.Manifest == "":
		return fmt.Errorf("meshcatalogclient: a module carries a verdict and no manifest digest")
	case (m.Verdict == VerdictRefused) != (len(m.Problems) > 0):
		return fmt.Errorf("meshcatalogclient: a module's problems are named only with a refusal, and a refusal names them")
	case m.Verdict == VerdictRefused && len(m.Warnings) > 0:
		return fmt.Errorf("meshcatalogclient: a refused module warns: a refusal names problems")
	}
	if m.Fp2 != "" {
		if _, err := KeyPart(m.Fp2); err != nil {
			return err
		}
	}
	if m.Manifest != "" {
		if _, err := ManifestsKey(m.Manifest); err != nil {
			return err
		}
	}
	return nil
}

func cleanInside(p string) bool {
	return p != "" && p == path.Clean(p) && !strings.HasPrefix(p, "/") && p != ".." && !strings.HasPrefix(p, "../")
}

// EncodeModule is m as JSON at the kept values' version; it refuses what CheckModule refuses.
func EncodeModule(m seat.ModulesByModuleValue) ([]byte, error) {
	if err := CheckModule(m); err != nil {
		return nil, err
	}
	m.V = keys.Version
	return json.Marshal(m)
}

// DecodeModule reads a `modules` value; it refuses an unknown version (keys.ErrUnknownVersion) and what EncodeModule refuses.
func DecodeModule(data []byte) (seat.ModulesByModuleValue, error) {
	if err := keys.CheckVersion(data); err != nil {
		return seat.ModulesByModuleValue{}, err
	}
	var m seat.ModulesByModuleValue
	if err := json.Unmarshal(data, &m); err != nil {
		return seat.ModulesByModuleValue{}, fmt.Errorf("meshcatalogclient: value does not fit its shape: %w", err)
	}
	if err := CheckModule(m); err != nil {
		return seat.ModulesByModuleValue{}, err
	}
	return m, nil
}