//! Content discovery and deserialization.
//!
//! Reads content.yaml, discovers campaigns and districts via directory
//! structure, deserializes YAML files into intermediate content types.
//! Comment-only YAML files (stubs) are skipped gracefully.

use std::collections::BTreeMap;
use std::path::{Path, PathBuf};

use crate::content::types::*;

/// All content loaded from disk, organized by district.
/// Inserted as a bevy Resource after loading completes.
#[derive(Debug, Default)]
pub struct ContentStore {
    pub manifest: Option<ContentManifest>,
    pub districts: BTreeMap<String, DistrictContent>,
}

/// Content for a single district.
#[derive(Debug, Default)]
pub struct DistrictContent {
    pub meta: Option<DistrictMeta>,
    pub district_path: PathBuf,
    pub pools: Vec<Pool>,
    pub templates: Vec<Template>,
    pub triangles: Vec<Triangle>,
    pub npc_profiles: Vec<NpcProfile>,
    pub locations: Vec<Location>,
    pub routines: Option<RoutineFile>,
    pub dialogue_pools: Vec<DialoguePool>,
    pub monologue_pools: Vec<MonologuePool>,
}

/// Errors that can occur during content loading.
#[derive(Debug, thiserror::Error)]
pub enum ContentError {
    #[error("IO error: {path}: {source}")]
    Io {
        path: PathBuf,
        source: std::io::Error,
    },
    #[error("YAML parse error: {path}: {source}")]
    Yaml {
        path: PathBuf,
        source: serde_yaml::Error,
    },
    #[error("Content manifest not found at {0}")]
    ManifestNotFound(PathBuf),
}

/// Load all content from the given root directory.
///
/// The root should contain `content.yaml` and the campaign directories.
/// Comment-only YAML stubs are skipped (logged at debug level).
pub fn load_content(content_root: &Path) -> Result<ContentStore, ContentError> {
    let mut store = ContentStore::default();

    // 1. Load content manifest
    let manifest_path = content_root.join("content.yaml");
    if !manifest_path.exists() {
        return Err(ContentError::ManifestNotFound(manifest_path));
    }
    let manifest: ContentManifest = load_yaml(&manifest_path)?;

    // 2. Discover districts for each enabled campaign
    for campaign in &manifest.campaigns {
        if !campaign.enabled {
            tracing::debug!("Skipping disabled campaign: {}", campaign.id);
            continue;
        }

        let campaign_path = content_root.join(&campaign.path);
        let district_dirs = discover_districts(&campaign_path);

        for district_dir in district_dirs {
            let district_id = derive_district_id(content_root, &district_dir);
            tracing::info!("Loading district: {} from {:?}", district_id, district_dir);

            let content = load_district(&district_dir)?;
            store.districts.insert(district_id, content);
        }
    }

    store.manifest = Some(manifest);
    Ok(store)
}

/// Discover district directories by recursively searching for district.yaml.
fn discover_districts(campaign_path: &Path) -> Vec<PathBuf> {
    let mut districts = Vec::new();
    let systems_path = campaign_path.join("systems");
    if systems_path.is_dir() {
        walk_for_districts(&systems_path, &mut districts);
    }
    // BTreeMap ordering guarantees deterministic district processing,
    // but sort the discovery order too for consistency.
    districts.sort();
    districts
}

/// Recursively walk directories looking for district.yaml files.
fn walk_for_districts(dir: &Path, results: &mut Vec<PathBuf>) {
    let Ok(entries) = std::fs::read_dir(dir) else {
        return;
    };

    // Collect and sort entries for deterministic traversal order
    let mut sorted_entries: Vec<_> = entries.filter_map(|e| e.ok()).collect();
    sorted_entries.sort_by_key(|e| e.file_name());

    for entry in sorted_entries {
        let path = entry.path();
        if path.is_dir() {
            let district_yaml = path.join("district.yaml");
            if district_yaml.exists() {
                results.push(path);
            } else {
                walk_for_districts(&path, results);
            }
        }
    }
}

/// Derive a district ID from its filesystem path.
/// e.g. campaigns/main/systems/krenn/stations/sova/districts/transit → krenn.sova.transit
fn derive_district_id(content_root: &Path, district_dir: &Path) -> String {
    let rel = district_dir
        .strip_prefix(content_root)
        .unwrap_or(district_dir);
    let components: Vec<&str> = rel
        .components()
        .filter_map(|c| c.as_os_str().to_str())
        .collect();

    // Extract meaningful path segments: system, station, district name
    // Path pattern: campaigns/{id}/systems/{system}/stations/{station}/districts/{district}
    let mut parts = Vec::new();
    let mut iter = components.iter().peekable();
    while let Some(&segment) = iter.next() {
        match segment {
            "systems" | "stations" | "districts" => {
                if let Some(&&name) = iter.peek() {
                    parts.push(name.to_string());
                    iter.next();
                }
            }
            _ => {}
        }
    }

    if parts.is_empty() {
        // Fallback: use the directory name
        district_dir
            .file_name()
            .and_then(|n| n.to_str())
            .unwrap_or("unknown")
            .to_string()
    } else {
        parts.join(".")
    }
}

/// Load all content for a single district directory.
fn load_district(district_dir: &Path) -> Result<DistrictContent, ContentError> {
    let mut content = DistrictContent {
        district_path: district_dir.to_path_buf(),
        ..Default::default()
    };

    // District metadata
    let meta_path = district_dir.join("district.yaml");
    if meta_path.exists() {
        match load_yaml::<DistrictMeta>(&meta_path) {
            Ok(meta) => content.meta = Some(meta),
            Err(e) => tracing::warn!("Failed to parse district metadata: {}", e),
        }
    }

    // Pools
    let pools_path = district_dir.join("pools.yaml");
    if pools_path.exists() {
        match load_yaml::<PoolFile>(&pools_path) {
            Ok(pool_file) => content.pools = pool_file.pools,
            Err(e) => tracing::warn!("Failed to parse pools: {}", e),
        }
    }

    // Templates
    let templates_dir = district_dir.join("templates");
    if templates_dir.is_dir() {
        content.templates = load_yaml_dir::<Template>(&templates_dir);
    }

    // Triangles
    let triangles_dir = district_dir.join("triangles");
    if triangles_dir.is_dir() {
        content.triangles = load_yaml_dir::<Triangle>(&triangles_dir);
    }

    // NPC profiles
    let npcs_dir = district_dir.join("npcs");
    if npcs_dir.is_dir() {
        content.npc_profiles = load_yaml_dir::<NpcProfile>(&npcs_dir);
    }

    // Locations
    let locations_dir = district_dir.join("locations");
    if locations_dir.is_dir() {
        content.locations = load_yaml_dir::<Location>(&locations_dir);
    }

    // Routines
    let routines_path = district_dir.join("routines").join("schedules.yaml");
    if routines_path.exists() {
        match load_yaml::<RoutineFile>(&routines_path) {
            Ok(routines) => content.routines = Some(routines),
            Err(e) => tracing::debug!("Skipping routines (stub or invalid): {}", e),
        }
    }

    // Dialogue pools
    let dialogue_dir = district_dir.join("dialogue");
    if dialogue_dir.is_dir() {
        content.dialogue_pools = load_yaml_recursive::<DialoguePool>(&dialogue_dir);
    }

    // Monologue pools
    let monologue_dir = district_dir.join("monologue");
    if monologue_dir.is_dir() {
        content.monologue_pools = load_yaml_recursive::<MonologuePool>(&monologue_dir);
    }

    let npc_count = content.npc_profiles.len();
    let triangle_count = content.triangles.len();
    let template_count = content.templates.len();
    let pool_count = content.pools.len();
    let dialogue_count = content.dialogue_pools.len();
    let monologue_count = content.monologue_pools.len();

    tracing::info!(
        "District loaded: {} NPCs, {} triangles, {} templates, {} pools, {} dialogue pools, {} monologue pools",
        npc_count, triangle_count, template_count, pool_count, dialogue_count, monologue_count
    );

    Ok(content)
}

/// Load and parse a single YAML file.
fn load_yaml<T: serde::de::DeserializeOwned>(path: &Path) -> Result<T, ContentError> {
    let text = std::fs::read_to_string(path).map_err(|e| ContentError::Io {
        path: path.to_path_buf(),
        source: e,
    })?;
    serde_yaml::from_str(&text).map_err(|e| ContentError::Yaml {
        path: path.to_path_buf(),
        source: e,
    })
}

/// Load all YAML files in a directory (non-recursive), skipping stubs.
fn load_yaml_dir<T: serde::de::DeserializeOwned>(dir: &Path) -> Vec<T> {
    let Ok(entries) = std::fs::read_dir(dir) else {
        return Vec::new();
    };

    let mut sorted_entries: Vec<_> = entries.filter_map(|e| e.ok()).collect();
    sorted_entries.sort_by_key(|e| e.file_name());

    let mut results = Vec::new();
    for entry in sorted_entries {
        let path = entry.path();
        if path.extension().and_then(|e| e.to_str()) != Some("yaml") {
            continue;
        }
        match load_yaml::<T>(&path) {
            Ok(item) => results.push(item),
            Err(e) => {
                // Check if this is a comment-only stub
                if is_comment_only_file(&path) {
                    tracing::debug!("Skipping stub file: {:?}", path);
                } else {
                    tracing::warn!("Failed to parse {:?}: {}", path, e);
                }
            }
        }
    }
    results
}

/// Load all YAML files recursively under a directory, skipping stubs.
fn load_yaml_recursive<T: serde::de::DeserializeOwned>(dir: &Path) -> Vec<T> {
    let mut results = Vec::new();
    walk_yaml_files(dir, &mut |path| {
        match load_yaml::<T>(path) {
            Ok(item) => results.push(item),
            Err(e) => {
                if is_comment_only_file(path) {
                    tracing::debug!("Skipping stub: {:?}", path);
                } else {
                    tracing::warn!("Failed to parse {:?}: {}", path, e);
                }
            }
        }
    });
    results
}

/// Walk a directory recursively, calling the callback for each .yaml file.
fn walk_yaml_files(dir: &Path, callback: &mut impl FnMut(&Path)) {
    let Ok(entries) = std::fs::read_dir(dir) else {
        return;
    };

    let mut sorted_entries: Vec<_> = entries.filter_map(|e| e.ok()).collect();
    sorted_entries.sort_by_key(|e| e.file_name());

    for entry in sorted_entries {
        let path = entry.path();
        if path.is_dir() {
            walk_yaml_files(&path, callback);
        } else if path.extension().and_then(|e| e.to_str()) == Some("yaml") {
            callback(&path);
        }
    }
}

/// Check if a YAML file contains only comments and whitespace (stub file).
fn is_comment_only_file(path: &Path) -> bool {
    let Ok(text) = std::fs::read_to_string(path) else {
        return false;
    };
    text.lines()
        .all(|line| line.trim().is_empty() || line.trim().starts_with('#'))
}

#[cfg(test)]
mod tests {
    use super::*;
    use std::fs;

    fn create_temp_content(dir: &Path) {
        // Create content.yaml
        fs::write(
            dir.join("content.yaml"),
            r#"version: "0.1.0"
campaigns:
  - id: test
    path: campaigns/test
    enabled: true
    discovery:
      districts: "systems/**/districts/*/district.yaml"
"#,
        )
        .unwrap();

        // Create district directory structure
        let district_dir = dir.join("campaigns/test/systems/alpha/stations/beta/districts/gamma");
        fs::create_dir_all(&district_dir).unwrap();

        // district.yaml
        fs::write(
            district_dir.join("district.yaml"),
            r#"display_name: "Test District"
description: "A test district"
locations: ["loc-a"]
npc_count: 2
"#,
        )
        .unwrap();

        // pools.yaml
        fs::write(
            district_dir.join("pools.yaml"),
            r#"pools:
  - pool_id: "test:pool_a"
    category: npc_role
    candidates:
      - npc_id: "npc:alice"
        weight: 1
"#,
        )
        .unwrap();

        // triangles/
        let tri_dir = district_dir.join("triangles");
        fs::create_dir_all(&tri_dir).unwrap();
        fs::write(
            tri_dir.join("test-triangle.yaml"),
            r#"canonical_id: test-triangle
display_name: "Test Triangle"
members:
  - npc: "npc:alice"
    role: "role-a"
  - npc: "npc:bob"
    role: "role-b"
  - npc: "npc:carol"
    role: "role-c"
forks: []
resolution_states: []
"#,
        )
        .unwrap();

        // templates/
        let tpl_dir = district_dir.join("templates");
        fs::create_dir_all(&tpl_dir).unwrap();
        fs::write(
            tpl_dir.join("test-site.yaml"),
            r#"template_id: test-site
display_name: "Test Site"
location: loc-a
role_slots:
  - role: worker
    display_name: "Worker"
    count: 1
    required: true
"#,
        )
        .unwrap();

        // npcs/ — one stub, one real
        let npc_dir = district_dir.join("npcs");
        fs::create_dir_all(&npc_dir).unwrap();
        fs::write(
            npc_dir.join("alice.yaml"),
            r#"canonical_id: alice
display_name: "Alice"
tier: 1
pattern: "FRIEND"
motivation: "HANDLER"
"#,
        )
        .unwrap();
        fs::write(
            npc_dir.join("bob.yaml"),
            "# NPC Profile: bob\n# canonical_id: test.bob\n",
        )
        .unwrap();
    }

    #[test]
    fn load_content_discovers_district() {
        let dir = std::env::temp_dir().join("sr_content_test_discover");
        let _ = fs::remove_dir_all(&dir);
        fs::create_dir_all(&dir).unwrap();
        create_temp_content(&dir);

        let store = load_content(&dir).unwrap();
        assert!(store.manifest.is_some());
        assert_eq!(store.districts.len(), 1);

        let (id, content) = store.districts.iter().next().unwrap();
        assert_eq!(id, "alpha.beta.gamma");
        assert!(content.meta.is_some());
        assert_eq!(content.meta.as_ref().unwrap().display_name, "Test District");

        let _ = fs::remove_dir_all(&dir);
    }

    #[test]
    fn load_content_parses_pools() {
        let dir = std::env::temp_dir().join("sr_content_test_pools");
        let _ = fs::remove_dir_all(&dir);
        fs::create_dir_all(&dir).unwrap();
        create_temp_content(&dir);

        let store = load_content(&dir).unwrap();
        let content = store.districts.values().next().unwrap();
        assert_eq!(content.pools.len(), 1);
        assert_eq!(content.pools[0].pool_id, "test:pool_a");
        assert_eq!(content.pools[0].candidates.len(), 1);

        let _ = fs::remove_dir_all(&dir);
    }

    #[test]
    fn load_content_parses_triangles() {
        let dir = std::env::temp_dir().join("sr_content_test_triangles");
        let _ = fs::remove_dir_all(&dir);
        fs::create_dir_all(&dir).unwrap();
        create_temp_content(&dir);

        let store = load_content(&dir).unwrap();
        let content = store.districts.values().next().unwrap();
        assert_eq!(content.triangles.len(), 1);
        assert_eq!(content.triangles[0].canonical_id, "test-triangle");
        assert_eq!(content.triangles[0].members.len(), 3);

        let _ = fs::remove_dir_all(&dir);
    }

    #[test]
    fn load_content_skips_stub_npcs() {
        let dir = std::env::temp_dir().join("sr_content_test_stubs");
        let _ = fs::remove_dir_all(&dir);
        fs::create_dir_all(&dir).unwrap();
        create_temp_content(&dir);

        let store = load_content(&dir).unwrap();
        let content = store.districts.values().next().unwrap();
        // Only alice.yaml should parse; bob.yaml is a stub
        assert_eq!(content.npc_profiles.len(), 1);
        assert_eq!(content.npc_profiles[0].canonical_id, "alice");

        let _ = fs::remove_dir_all(&dir);
    }

    #[test]
    fn load_content_parses_templates() {
        let dir = std::env::temp_dir().join("sr_content_test_templates");
        let _ = fs::remove_dir_all(&dir);
        fs::create_dir_all(&dir).unwrap();
        create_temp_content(&dir);

        let store = load_content(&dir).unwrap();
        let content = store.districts.values().next().unwrap();
        assert_eq!(content.templates.len(), 1);
        assert_eq!(content.templates[0].template_id, "test-site");
        assert_eq!(content.templates[0].role_slots.len(), 1);

        let _ = fs::remove_dir_all(&dir);
    }

    #[test]
    fn derive_district_id_from_path() {
        let root = Path::new("/content");
        let district = Path::new("/content/campaigns/main/systems/krenn/stations/sova/districts/transit");
        let id = derive_district_id(root, district);
        assert_eq!(id, "krenn.sova.transit");
    }

    #[test]
    fn is_comment_only_detects_stubs() {
        let dir = std::env::temp_dir().join("sr_content_test_comment");
        let _ = fs::remove_dir_all(&dir);
        fs::create_dir_all(&dir).unwrap();

        let stub = dir.join("stub.yaml");
        fs::write(&stub, "# comment\n# another\n").unwrap();
        assert!(is_comment_only_file(&stub));

        let real = dir.join("real.yaml");
        fs::write(&real, "key: value\n").unwrap();
        assert!(!is_comment_only_file(&real));

        let _ = fs::remove_dir_all(&dir);
    }

    #[test]
    fn role_count_range_deserialization() {
        // RoleCount::Range uses untagged enum — verify {min, max} object parses
        let yaml = r#"
template_id: test
display_name: "Test"
role_slots:
  - role: worker
    display_name: "Worker"
    count:
      min: 2
      max: 4
    required: true
  - role: manager
    display_name: "Manager"
    count: 1
    required: true
"#;
        let template: crate::content::types::Template =
            serde_yaml::from_str(yaml).expect("template with RoleCount::Range should parse");
        assert_eq!(template.role_slots.len(), 2);

        match &template.role_slots[0].count {
            crate::content::types::RoleCount::Range { min, max } => {
                assert_eq!(*min, 2);
                assert_eq!(*max, 4);
            }
            other => panic!("Expected RoleCount::Range, got {:?}", other),
        }

        match &template.role_slots[1].count {
            crate::content::types::RoleCount::Fixed(n) => assert_eq!(*n, 1),
            other => panic!("Expected RoleCount::Fixed, got {:?}", other),
        }
    }

    #[test]
    fn pool_constraint_deserialization() {
        // PoolConstraint uses untagged enum — verify both variants parse
        let yaml = r#"
pools:
  - pool_id: "test:pool"
    category: npc_role
    constraints:
      - must_be_in_template: "logistics-hub"
      - must_have_pattern: "FRIEND"
      - bonded_character: "smuggler"
    candidates:
      - npc_id: "npc:alice"
        weight: 1
"#;
        let pool_file: crate::content::types::PoolFile =
            serde_yaml::from_str(yaml).expect("pool with constraints should parse");
        assert_eq!(pool_file.pools.len(), 1);
        assert_eq!(pool_file.pools[0].constraints.len(), 3);

        // All constraints in this format are key-value strings (plain scalars)
        // which match PoolConstraint::KeyValue
        for constraint in &pool_file.pools[0].constraints {
            match constraint {
                crate::content::types::PoolConstraint::KeyValue(s) => {
                    assert!(!s.is_empty());
                }
                crate::content::types::PoolConstraint::Structured(_) => {
                    // Structured constraints are also valid
                }
            }
        }
    }
}